The attached .ics file ("foo.ics") contains a recurring event.

If i use Thunderbird's "File » Open » Calendar File…" to open this, it
creates a new calendar named "redacted", and the event shows up as
expected (on 2022-03-02).

If i right-click the event in the calendar view, and choose "edit", i
get an option "Edit only this occurence" or "Edit all occurrences".

If i choose "Edit only this occurrence", the edit dialog box appears,
but i cannot change which calendar it is in (i cannot move it to a
different calendar, because the "Calendar:" entry dropdown field is
grayed out.

If i choose "Edit all occurrences", the Calendar: dropdown is enabled,
but the edit view contains no information but the starting date/time: no
title, ending time is the same as start time, no location, etc.  And
indeed i cannot even save the event properly in this case without
entering something for the title.

I've tried this with a brand new profile, and see the same problem
repeatedly.

It's entirely possible that this is a malformed .ics file, but it is a
copy of a text/calendar attachment that i received from an Outlook
client via Office365, with various content fields redacted: i changed
nothing related to date/time, but redacted participant names, location
URLs, etc.

It's also entirely possible that this is an upstream bug.  If you think
i should forward it upstream, please let me know.

Thanks for maintaining Thunderbird in Debian!