Hello Jason
It does sound like an unusual issue you’re encountering. The maximum 14 command should indeed limit the number of backup configurations to 14. It does sound like a bug, especially since some of your devices are functioning correctly while others are not.
The following link verifies the behavior of the archive feature when issuing the maximum command.
Specifically, it states the following:
After the maximum number of files has been saved in the archive, the oldest file is automatically deleted when the next, most recent file is saved.
If you have a Cisco contract, I suggest you open a TAC case since this is indeed unexpected behavior. Let us know how you get along!
I hope this has been helpful!
Laz