Well, thing is I don’t need to know if Harvesters are set up properly or no, because I know they are - they are reflected in GUI in the ‘Harvesters’ field and total plots count adds up if count each Harvester separately and what I see GUI’s ‘Total’ field.
Log is set to INFO from the start, so, I checked Harvesters logs:
for example like this:
2021-08-07T05:30:11.232 harvester chia.plotting.plot_tools: INFO Loaded a total of 2830 plots of size 280.0992603533832 TiB, in 3.8783962726593018 seconds
2021-08-07T05:30:12.135 harvester chia.harvester.harvester: INFO 11 plots were eligible for farming 8eca0932a1... Found 0 proofs. Time: 4.78147 s. Total 2830 plots
2021-08-07T05:30:17.953 harvester chia.harvester.harvester: INFO 5 plots were eligible for farming 8eca0932a1... Found 0 proofs. Time: 1.12897 s. Total 2830 plots
2021-08-07T05:30:28.008 harvester chia.harvester.harvester: INFO 5 plots were eligible for farming 8eca0932a1... Found 0 proofs. Time: 0.58509 s. Total 2830 plots
2021-08-07T05:30:36.659 harvester chia.harvester.harvester: INFO 8 plots were eligible for farming 8eca0932a1... Found 0 proofs. Time: 0.98422 s. Total 2830 plots
2021-08-07T05:30:45.260 harvester chia.harvester.harvester: INFO 7 plots were eligible for farming 8eca0932a1... Found 0 proofs. Time: 0.94221 s. Total 2830 plots
2021-08-07T05:30:54.913 harvester chia.harvester.harvester: INFO 6 plots were eligible for farming 8eca0932a1... Found 0 proofs. Time: 1.26488 s. Total 2830 plots
2021-08-07T05:31:05.432 harvester chia.harvester.harvester: INFO 9 plots were eligible for farming 8eca0932a1... Found 0 proofs. Time: 0.86820 s. Total 2830 plots
2021-08-07T05:31:16.210 harvester chia.harvester.harvester: INFO 3 plots were eligible for farming 8eca0932a1... Found 0 proofs. Time: 0.54923 s. Total 2830 plots
2021-08-07T05:31:28.165 harvester chia.harvester.harvester: INFO 9 plots were eligible for farming d3f5c451fe... Found 0 proofs. Time: 1.17513 s. Total 2830 plots
2021-08-07T05:31:36.854 harvester chia.harvester.harvester: INFO 5 plots were eligible for farming d3f5c451fe... Found 0 proofs. Time: 0.64615 s. Total 2830 plots
2021-08-07T05:31:46.147 harvester chia.harvester.harvester: INFO 7 plots were eligible for farming d3f5c451fe... Found 0 proofs. Time: 0.60614 s. Total 2830 plots
2021-08-07T05:31:54.363 harvester chia.harvester.harvester: INFO 5 plots were eligible for farming d3f5c451fe... Found 0 proofs. Time: 0.66615 s. Total 2830 plots
2021-08-07T05:32:04.728 harvester chia.harvester.harvester: INFO 12 plots were eligible for farming d3f5c451fe... Found 0 proofs. Time: 0.95021 s. Total 2830 plots
2021-08-07T05:32:13.423 harvester chia.plotting.plot_tools: INFO Searching directories ['E:\\Chia', 'I:\\Chia', 'F:\\Chia', 'G:\\Chia', 'H:\\Chia', 'L:\\chia', 'K:\\chia', 'J:\\Chia', 'M:\\Chia', 'N:\\Chia', 'O:\\Chia', 'P:\\Chia', 'Q:\\Chia', 'G:\\ChiaN', 'I:\\Chian', 'P:\\ChiaN', 'R:\\Chia', 'N:\\Chian', 'M:\\Chian', 'D:\\Box1\\Chian', 'D:\\Box2\\Chian', 'D:\\Box3\\Chian', 'D:\\Box4\\Chian', 'D:\\Box5\\Chian', 'D:\\Box6\\Chian', 'K:\\Chian', 'J:\\Chian', 'E:\\Chian', 'D:\\Box7\\Chian']
2021-08-07T05:32:13.457 harvester chia.plotting.plot_tools: WARNING Directory: K:\chia does not exist.
or this on another Harvester:
-31T09:23:21.144 harvester chia.plotting.plot_tools: INFO Loaded a total of 669 plots of size 66.53616461728598 TiB, in 0.38660550117492676 seconds
2021-07-31T09:23:21.355 harvester chia.harvester.harvester: INFO 1 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.59739 s. Total 669 plots
2021-07-31T09:23:34.659 harvester chia.harvester.harvester: INFO 3 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.27771 s. Total 669 plots
2021-07-31T09:23:45.922 harvester chia.harvester.harvester: INFO 2 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.24874 s. Total 669 plots
2021-07-31T09:23:56.145 harvester chia.harvester.harvester: INFO 2 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.46553 s. Total 669 plots
2021-07-31T09:24:07.004 harvester chia.harvester.harvester: INFO 0 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.15184 s. Total 669 plots
2021-07-31T09:24:15.519 harvester chia.harvester.harvester: INFO 3 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.24275 s. Total 669 plots
2021-07-31T09:24:24.447 harvester chia.harvester.harvester: INFO 0 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.13786 s. Total 669 plots
2021-07-31T09:24:33.341 harvester chia.harvester.harvester: INFO 0 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.18181 s. Total 669 plots
2021-07-31T09:24:42.832 harvester chia.harvester.harvester: INFO 0 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.16183 s. Total 669 plots
2021-07-31T09:24:52.624 harvester chia.harvester.harvester: INFO 2 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.42357 s. Total 669 plots
2021-07-31T09:25:02.565 harvester chia.harvester.harvester: INFO 0 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.12887 s. Total 669 plots
2021-07-31T09:25:11.294 harvester chia.harvester.harvester: INFO 1 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.27172 s. Total 669 plots
2021-07-31T09:25:20.505 harvester chia.harvester.harvester: INFO 1 plots were eligible for farming eee5224133... Found 0 proofs. Time: 0.45154 s. Total 669 plots
or this from my Farmer Machine:
This is little bit less clear to me, but all in all seems in line and everything is working smoothly.
2021-08-06T19:03:57.083 harvester chia.harvester.harvester: INFO 4 plots were eligible for farming 3b5a8ab52b... Found 0 proofs. Time: 0.64010 s. Total 2170 plots
2021-08-06T19:03:58.708 full_node chia.full_node.full_node: INFO Added unfinished_block d31e0250d25702440ac04def1f6da0ac0c22eb480b7a9bc9a425fdc150b36f4e, not farmed by us, SP: 10 farmer response time: 2.265185832977295, Pool pk xch1j4dh3z6mngmlms7l9f6hajkp7a8au0vmfxxxxxxxxxxxxxxxxxxx, validation time: 0.14063715934753418, cost: 363681930, percent full: 3.306%
2021-08-06T19:04:00.989 full_node chia.full_node.full_node: INFO Updated peak to height 677975, weight 720080384, hh f26cf10a7eae0c396c94a6f3c821eaf80d4948611173ab7926e1b4xxxxxxx, forked at 677974, rh: 2d17931bd284d1147a2d33a7e15f76e44b2b6f3e290123bdc2ec05b25xxxxxx, total iters: 2358320686223, overflow: False, deficit: 9, difficulty: 2640, sub slot iters: 130023424, Generator size: 9983, Generator ref list size: 0
2021-08-06T19:04:00.989 full_node chia.full_node.mempool_manager: INFO add_spendbundle took 0.0 seconds, cost 61829 (0.001%)
2021-08-06T19:04:00.989 full_node chia.full_node.mempool_manager: INFO add_spendbundle took 0.0 seconds, cost 18175415 (0.165%)
2021-08-06T19:04:00.989 full_node chia.full_node.mempool_manager: INFO add_spendbundle took 0.0 seconds, cost 10868858 (0.099%)
2021-08-06T19:04:00.989 full_node chia.full_node.mempool_manager: INFO add_spendbundle took 0.0 seconds, cost 41414384 (0.376%)
2021-08-06T19:04:00.989 full_node chia.full_node.mempool_manager: INFO add_spendbundle took 0.0 seconds, cost 31796662 (0.289%)
2021-08-06T19:04:01.005 full_node chia.full_node.mempool_manager: INFO Size of mempool: 5 spends, cost: 102317148 minimum fee to get in: 0
2021-08-06T19:04:01.005 full_node chia.full_node.full_node: INFO Block validation time: 0.8906936645507812, cost: 261673927, percent full: 2.379%
2021-08-06T19:04:01.083 wallet chia.wallet.wallet_blockchain: INFO Updated wallet peak to height 677975, weight 720080384,
2021-08-06T19:04:01.739 full_node chia.full_node.mempool_manager: INFO It took 0.015625476837158203 to pre validate transaction
2021-08-06T19:04:01.739 full_node chia.full_node.mempool_manager: INFO add_spendbundle took 0.0 seconds, cost 18439459 (0.168%)
2021-08-06T19:04:02.192 full_node chia.full_node.full_node: INFO Added unfinished_block 04cccf868b2fee9f044829cf6f6e250eb1868f3ddfa9f1abfaab17xxxxxx, not farmed by us, SP: 10 farmer response time: 5.749508857727051, Pool pk xch1f0ryxk6qn096hefcwrdwpuph2hm24w69jnzezhkfswk0z2xxxxxx, validation time: 0.14063549041748047, cost: 363681930, percent full: 3.306%
2021-08-06T19:04:03.317 full_node chia.full_node.full_node: INFO Duplicate compact proof. Height: 195224. Header hash: 05b6c21999c71b39917d9a93b4c2732ac9ee18f75fb64c87b052bb4axxxxx.
2021-08-06T19:04:06.177 full_node chia.full_node.full_node: INFO Finished signage point 11/64: CC: 4225ab19a004743688529a7a5def36599c3679a75ab9c5828e6c32446xxxxx RC: f12a864085fc209cae9560ec273b90737955aaec9fb8c09117de93e45xxxxxxx
so, everything seems in OK with timings and such.
The question though still stands - why 1 of my 4 harvesters has the message (in my initial post) and others don’t, although I know this is probably fine, I am still curious 
Thanks!