SmartGuard fails to delete old Snapshots

I have SmartGuard set to retain 5 snapshots which is the last three daily, the last weekly, and the last monthly. That used to work, but without changing any settings, SmartGuard simply stopped deleting snapshots. By the time my VM file had grown so large that the drive it's on was running out of free space, there were EIGHTEEN Snapshots. Of course, as we all know, deleting them takes a LONG time, so I'm having to leave the Windows VM open for several days to manually get rid of all of them.
The SmartGuard setting is still set to retain ONLY FIVE Snapshots.
What can be done to get it to once again delete a Snapshot before it starts to record what would be the sixth one?

 

Hi @milleron , please delete the unwanted snapshots and try uninstalling and reinstalling Parallels Desktop for Mac and check if that helps.