Initially found by Rhonda on bug 31333, the problem seems to affect all system preferences using the patron category multi-select feature: To test: * Search for the OPACHoldsIfAvailableAtPickupExceptions system preference * Check some patron categories and save * Uncheck all patron categories and save - it says 'nothing to save' * Reload the page or search for OPACHoldsIfAvailableAtPickupExceptions again * The selected values remain and cannot all be removed
*** This bug has been marked as a duplicate of bug 31364 ***