Recurring events in calendar won't save timezone offset

In calendar event properties, it’s possible to choose a different timezone for the start or finish time. This works well for standalone events, but is overridden when the event recurs. Even if the timezone offset was already saved, adding recurrence will reset it to the home timezone. There is no visible error message when this happens.

The only workaround I can see is to temporarily change the Windows system timezone so I can create the event without needing an offset, and set up recurrence. If I do that the event will be saved correctly, but if I edit it again after returning Windows to the correct timezone, the problem happens again.