Keywords not parsed in commit message

Using both the default angular based syntax (e.g. feat: my feature summary) and custom keywords (e.g. FEATURE:minor) in the action inputs does not trigger the appropriate bump in the version, only the default patch bump. I've tried using "fix:", "fix(scope):, etc., but none of them seem to work.

Any ideas where i'm going wrong here?

Run mathieudutour/github-tag-action@v5.6
with:
    github_token: ***
    custom_release_rules: MAJOR:major,MINOR:minor,PATCH:patch, FIX:patch, BUG:patch, FEATURE:minor
    default_bump: patch
    tag_prefix: v
    release_branches: master,main
    create_annotated_tag: false
    fetch_all_tags: false
    dry_run: false

Previous tag was v0.1.16, previous version was 0.1.16.
Analyzing commit: Update Build_Prerelease_Deploy.yml

FEATURE: Test bump
The commit should not trigger a release
Analysis of 1 commits complete: no release
New version is 0.1.17.
New tag after applying prefix is v0.1.17

No source file or test is named. Start by reproducing the shown workflow configuration and tracing the action's custom_release_rules and commit-message parsing entry points; done means a commit containing FEATURE: Test bump produces the expected minor version bump.