I enabled commit-status preset in diagnostics and I see in the teamcity-commit-status.log entries that pull request build was started and that the build finished. But when I go to the bitbucket UI for this PR, no build results can be seen. No errors in the teamcity-commit-status.log reported.
Surprisingly, there are some other TeamCity config and some other Bitbucket repositories, and Commit Status Publisher works well.
The project is very simple, it has just 1 vcs.
Unforutnately, teamcity-commit-status.log is not informative and does NOT include actul REST URLS that were called so that I could check that it formed the API call properly.