As a test and keep people commenting to retain a 'Comment Badge', I set up a simple badge that required 1 comment and expired in 30 days.
Also set to display
Interestingly, my test (as Admin too) had the Award given and published at Credly but:
 The Comment award was never displayed on the site
 The Award expiration was set to the next day - see screenshot
No idea if this has anything to do with the date/time format being used.