Internal Server Error when syncing Calendar

[GeorgeCraggs]

I've recently installed the latest version (0.34.0) on macOS. My contacts have all synced without issues, but calendar fails with a 500 error. The calendar app on macOS gives a 500 error, but I also get an error if I try to access from the collection list at https://localhost:37358. I can access the calendar fine when signed in at https://pim.etesync.com/pim/events.

In the logs I get the following (there's normally a number of the first line, followed by the last line once). I've replaced my username and the file identifiers for privacy.

[2025-02-07 08:29:57 +0000] [1517/Thread-592 (process_request_thread)] [ERROR] 'GMT Standard Time'
[2025-02-07 08:29:57 +0000] [1517/Thread-592 (process_request_thread)] [ERROR] An exception occurred during REPORT request on '/<Username>/<Random>/': Failed to serialize item '<Random2>.ics' from '<Username>/<Random>': 'VTIMEZONE components must contain a valid TZID'

I also noticed the following lines, but unsure if they are relevant.

[2025-02-07 08:35:44 +0000] [1517/Thread-612 (process_request_thread)] [WARNING] Bad PROPPATCH request on '/<Username>/<Random3>/': Value of 'mtime' must be 'str' not 'int': 1730800742960
[2025-02-07 08:35:44 +0000] [1517/Thread-612 (process_request_thread)] [INFO] PROPPATCH response status for '/<Username>/<Random3>/' in 0.005 seconds: 400 Bad Request