Editing time of event with unprefixed TZID strips time zone (converting it to floating time)
On a system with a time zone of Europe/London (currently UTC+1, at time of this bug filing) an event with the following:
is correctly displayed in Calendar as 13:00-14:00.
Editing the event in Calendar to change the time to 14:00-15:00 results in:
I.e. the times have been changed to reflect the input values, but the time zone information has been stripped, resulting in a "floating time" event. Calendar also then immediately displays the floating time event incorrectly as well (treating it as UTC instead of local) - I'll file a separate bug for that.
An event with a TZID containing a registry prefix (for example Evolution) correctly retains the TZID after editing in GNOME Calendar. Example VEVENT fields: