Artifacts are not cleaned up (Team City 9.1.6 Enterprise)

We are using TeamCity Enterprise 9.1.6 (build 37459). I have a minimal build configuration that has a single Power Shell build step that creates a new file:

  New-Item new_file.txt -type file

I have also configured the below artifact paths:

  new_file.txt => test.zip

Under the Clean-up rules I have set the following rule for artifacts for a build configuration:

  Artifacts older than the 1st successful build; artifact patterns: +:**/*

Meaning that only one artifact should be kept. I have now run the build several times but it keeps artifacts for all builds:

Why are the artifacts not cleaned up? I took a look at the data directory:

And they are all there. What am I missing?

Notice:

1. The builds are NOT pinned
2. The build is NOT used as a source for artifact dependency in other builds
3. The build is NOT used as a snapshot dependency in other builds
4. No builds were manually deleted within the last day.

I also looked at:

https://teamcity-support.jetbrains.com/hc/en-us/community/posts/206829295-clean-up-not-removing-artifacts?input_string=Artifacts%20are%20not%20cleaned%20up%20(Team%20City%20enterprise)

and:

https://teamcity-support.jetbrains.com/hc/en-us/community/posts/206169269-Old-artifacts-are-not-deleted?input_string=Artifacts%20are%20not%20cleane

But did not find an answer.

/Johannes