When everything works as expected we see something like this in the log of a Jenkins build:

Posting build status of INPROGRESS to Bitbucket Server for commit id [18590112a773ec5a48f5c89c16de99d3fb16d903] and ref 'refs/heads/working'

When the build finishes up we see something like this in the log:

Posting build status of SUCCESSFUL to Bitbucket Server for commit id [18590112a773ec5a48f5c89c16de99d3fb16d903] and ref 'refs/heads/working'

Sometimes we can even see Jenkins trying several times to report the result to the Bitbucket Server.

The problem is that sometimes we do not even see Jenkins trying to report any build status to the Bitbucket Server, not when the build starts and not when it ends.

We do quite consistently see that one of our multibranch-pipeline-job does not report build status to the Bitbucket Server, but a down-stream job triggered from that  same pipeline, using the same repo and Branch Sources configuration, does report build status to the Bitbucket Server.

We cannot yet upgrade the plugin from 3.6.0 to 4.x due to the bug reported in JENKINS-72120.