Change Tracking clenup

Is there a way to know when cleanup of change tracking tables occurs? How to check last occurrence of cleanup process?

BACKGROUND:

I have Change Tracking on database (retention = 1 minute):

ALTER DATABASE [test] SET CHANGE_TRACKING = ON (CHANGE_RETENTION = 1 MINUTES)

I do some updates in my test table and then wait a bit more than retention period (lets say 3 minutes). As the cleanup process is async, I do understand that there NO guaranty that CT tables will be cleaned up after 1 minute. It can happen any time that is > 1 min.

I found this proc to call cleanup process manually:

EXEC sp_flush_commit_table_on_demand 100000

But it does not work as expected.. (Change Tracking rows are still in place after retention period)