Pipelines not assigning to commits

Me and my partner are working on a project. We don’t use groups, I just added him as a ‘Member’ with ‘Developer’ rights to a private project.
The issue is, whenever he makes a commit, there are no pipelines triggered. And so, he gets email notification that pipeline has failed. If I commit into the same branch, everything works as expected.

I am providing an example of CI that I expect to work for both of us.

stage: test
- “mvn $MAVEN_CLI_OPTS -B -s ci_settings.xml”
- master

Notice, except master is here, I expect this stage to work on any other branch.

Example of an issue, with same branch but two different authors