The merge request jenkins plugin had quite a major bug.
It would add comments to the wrong merge request. For example: The following shows a merge request for TRY-CDW-20492 with id of 30.
But, merge request 30 wasn’t for TRY-CDW-20492; it was for TRY-PP-20702.
This bug was fixed here but isn’t available as an updated plugin on jenkins-ci.
I have uploaded my build here for now and it resolves my issue.