Another user with UberCalendar where the colours keep changing for no apparent reason. I use Google Calendars and manage 13 colour-coded calendars. I will add one other issue to the thread, though, is that some calendars are marked "off" in the preferences and after a few days show up again. So I don't only have to reset colour scheme for some calendars (not all), I also have to mark other calendars "off".

Strange behaviour indeed.