The last Thunderbird / Lightning update has caused a problem with my calendar updates. My categories disappear. I had created some "custom" categories for events. I generally use these with recurring events to mark off when something has been taken care of for that month. I click on the event, select "Edit only this occurrence", select my custom category from the list, save and close. When I first save the event, it disappears from my calendar list (I have "Events in the next 31 days" selected), but then when I refresh, it reappears. Prior to the update, this would show the event with its newly assigned category. Now, the category might show up initially, but if I close Thunderbird and re-open, or even just return to the calendar after a day, the category does not show. How can I get my categories to "stick"? I don't see this problem mentioned in the list of possible update problems.