When I set the holidays in korganizer 5.1.3 to Germany (German), after a few seconds or a minute, it is set back to none. Same with the working period. Reproducible: Always Steps to Reproduce: 1. set holidays to Germany (German) 2. wait a minute 3. check the settings Actual Results: setting is set back to none Expected Results: expect the settings not to change Kontact summery does not show holidays, but it is set to show holidays. kalarm does not consider holidays.
Same on Arch / KOrganizer 16.04.1
Similar problem here in openSUSE (with KDE Applications 16.04.1/Korganizer 5.2.1 and Qt 5.6.0). The setting does stick (longer than a minute), but there are no holidays shown at all. And after quitting and restarting Korganizer, it is back to "(None)", so it doesn't seem to be saved either.
Fixed in 5.3.0.