Unable to change state of "Do not backup vm"

I'm using Parallels 7 on mountain lion (upgraded from 6).

Currently the checkbox is unselected. I can reselect it and then close the configuration window, but when I open the configuration again the setting remains unselected.

My Time Machine settings do not show exclusion of the pvm file (the "Exclude these item from backups"-list is empty), but the command: sudo mdfind "com_apple_backup_excludeItem = 'com.apple.backupd'"
still lists the vm file: /Users/xyz/Documents/Parallels/Windows 7.pvm

Searching the forum I found and tried this http://kb.parallels.com/en/112152
(running the command: sudo tmutil removeexclusion -p "/Users/xyz/Documents/Parallels/Windows 7.pvm")
with no avail.

I have had to resort to do manual backups of the pvm file, but it's excruciating annoying.


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UPDATE:

Managed to remove the pvm file from the exclusion list with: sudo tmutil removeexclusion "/Users/xyz/Documents/Parallels/Windows 7.pvm" (note: omission of the -p option)
Verified it was removed with the command: sudo mdfind "com_apple_backup_excludeItem = 'com.apple.backupd'"
As a result Time Machine made a backup of the pvm file
The UI (configuration window) however still isn't right so it's likely "just" UI bug (as in: I can check it, and the pvm file is listed in the exclusion list again, but the checkbox doesnt stay checked).