dotCover 2021.3.2 in Rider 2021.3.2 coverage report gives inconsistent results for Unity 2020.3.24f1 project

I have Unity project with editor Unity tests. I use C#.
When I run dotCover over the tests, the obtained report shows inconsistent results:
- analysis two tests may be reported to give less coverage than analyzing same tests separately;
- same tests show different coverage results from launch to launch;
- coverage report may show some lines "not covered" even when I have breakpoints hit in those lines (!)

Tests are consistent, the code is not changed between sessions, no random data is used, etc. 
I tried to reinstall Rider and dotCover, re-imported my Unity project.
Only 1 test can be ran (no parallel tests enabled).

Please advise. Thank you