Merge with when condition

UPDATES:

Fake error, the reason why I don’t get it run, because I create a branch name which is not started by feature

The question

I set a pipeline step with when condition:

when:
  branch: [master, feature/* ]
  event: [push, pull_request, tag]

I found when the merge is approved and codes were merged to master branch. It triggers a build. But above step with this when condition is skipped and not run by drone pipeline.