This is Bitbucket Server 5.12.2. It looks like it falls into check for BRANCH ref change, while the actual notification had a TAG here.
Same issue with 5.15.0
Any new update ? same error , BitBucket v5.16.0
Liam Newman submitted a pull request: https://github.com/jenkinsci/bitbucket-branch-source-plugin/pull/230
Let me know if you have any concerns. Cheers.
Any update on this ticket? Tag build is not getting triggered on Bitbucket Branch Source Plugin 2.5.0 version also. Thank you.