Hi There, My Thunderbird calendar data has suddenly disappeared. Thunderbird version 78.14.0. Installed 17/11/16 and last updated 09/09/21. Set up on a Macbook Pro using macOS Sierra 10.12 Whilst using my calendar on Thunderbird yesterday I was editing an event, the edit didn't save properly and reverted to the original event data. This repeated on the 2nd attempt at editing the event, and then some of the calendar data disappeared. The next minute all the calendar data disappeared. I have a number of calendars set up within thunderbird, and these are all still listed (with their colours) in the task bar on the left. But the actual calendar data is gone. The function to create an event still works - but when I save the event it does not appear. All the calendars are 'unhidden' See attached screenshot. I used to use the lightning extension, however I believe with this version of thunderbird the calendar is integrated with no add on/extension. I have checked the add-on section and nothing is showing. Any help is appreciated as I run my life (and various businesses and projects) through my thunderbird calendar, and am currently stuck. Please note I am not too familiar with the back-end of a mac, so any instructions to access thunderbird files would be helped with an explanation of where they can be located on a mac. Many thanks