Issue:
Running build is not aborted even though "Rolling builds" is enabled.
Possible solution:
For a running build to be aborted, the new build must be using the same workflow against the same branch. Check to make sure the build you expect to be aborted is using the same workflow against the same branch.
Depending on what you are trying to do, you might want to consider using [skip ci] to prevent a build from being triggered.
Additional info:
For information on "Rolling builds": https://devcenter.bitrise.io/builds/rolling-builds/
For information on [skip ci]: https://devcenter.bitrise.io/builds/triggering-builds/skipping-a-given-commit-or-pull-request/