Problem with ICS calendar

[odin568]

Hi,
I use icsx a lot and never had issues.
Now for our local fire department, we switched tool and have a service, which produces ics calendars.
This behaves strange for some events.

I imported the calendar with latest icsx version to multiple mobile phones and thereby also multiple calendar apps (google, acalendar, simple kalender, ...) - all same issue.

This is the full ICS:

BEGIN:VCALENDAR
PRODID:-//eluceo/ical//2.0/EN
VERSION:2.0
CALSCALE:GREGORIAN
BEGIN:VEVENT
UID:20231211T11044248258
DTSTAMP:20231211T110442
LAST-MODIFIED:20231211T110819
SUMMARY:Test-Appointment
DESCRIPTION:
URL:https://www.firemanager.de
DTSTART;TZID=Europe/Berlin:20240102T160000
DTEND;TZID=Europe/Berlin:20240102T200000
LOCATION:
CATEGORIES:TEST
STATUS:CONFIRMED
END:VEVENT
BEGIN:VEVENT
UID:20231209T19312648259
DTSTAMP:20231209T193126
LAST-MODIFIED:20231211T112213
SUMMARY:Mitgliederversammlung
DESCRIPTION:
URL:https://www.firemanager.de
DTSTART;TZID=Europe/Berlin:20240106T190000
DTEND;TZID=Europe/Berlin:20240106T220000
LOCATION:
CATEGORIES:TEST
STATUS:CONFIRMED
END:VEVENT
BEGIN:VEVENT
UID:20231209T17291547999
DTSTAMP:20231209T172915
LAST-MODIFIED:20231209T172915
SUMMARY:Atemschutz Theorie
DESCRIPTION:
URL:https://www.firemanager.de
DTSTART;TZID=Europe/Berlin:20240112T193000
DTEND;TZID=Europe/Berlin:20240112T213000
LOCATION:Feuerwehrhaus
CATEGORIES:Atemschutz
STATUS:CONFIRMED
END:VEVENT
BEGIN:VEVENT
UID:20231209T20173148093
DTSTAMP:20231209T201731
LAST-MODIFIED:20231209T201731
SUMMARY:Atemschutzübung
DESCRIPTION:
URL:https://www.firemanager.de
DTSTART;TZID=Europe/Berlin:20240314T193000
DTEND;TZID=Europe/Berlin:20240314T213000
LOCATION:Feuerwehrhaus
CATEGORIES:Atemschutz
STATUS:CONFIRMED
END:VEVENT
BEGIN:VEVENT
UID:20231209T20173148094
DTSTAMP:20231209T201731
LAST-MODIFIED:20231209T201731
SUMMARY:Atemschutzübung
DESCRIPTION:
URL:https://www.firemanager.de
DTSTART;TZID=Europe/Berlin:20240418T193000
DTEND;TZID=Europe/Berlin:20240418T213000
LOCATION:Feuerwehrhaus
CATEGORIES:Atemschutz
STATUS:CONFIRMED
END:VEVENT
BEGIN:VTIMEZONE
TZID:Europe/Berlin
BEGIN:STANDARD
DTSTART:20240102T000000
TZNAME:CET
TZOFFSETTO:+0100
TZOFFSETFROM:+0100
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:20240331T030000
TZNAME:CEST
TZOFFSETTO:+0200
TZOFFSETFROM:+0100
END:DAYLIGHT
END:VTIMEZONE
END:VCALENDAR

When I compare two events, i.e. the first "Test-Appointment"...

BEGIN:VEVENT
UID:20231211T11044248258
DTSTAMP:20231211T110442
LAST-MODIFIED:20231211T110819
SUMMARY:Test-Appointment
DESCRIPTION:
URL:https://www.firemanager.de
DTSTART;TZID=Europe/Berlin:20240102T160000
DTEND;TZID=Europe/Berlin:20240102T200000
LOCATION:
CATEGORIES:TEST
STATUS:CONFIRMED
END:VEVENT

with i.e. the wrong "Atemschutz Theorie" event...

BEGIN:VEVENT
UID:20231209T17291547999
DTSTAMP:20231209T172915
LAST-MODIFIED:20231209T172915
SUMMARY:Atemschutz Theorie
DESCRIPTION:
URL:https://www.firemanager.de
DTSTART;TZID=Europe/Berlin:20240112T193000
DTEND;TZID=Europe/Berlin:20240112T213000
LOCATION:Feuerwehrhaus
CATEGORIES:Atemschutz
STATUS:CONFIRMED
END:VEVENT

... I see no structural issue with this.
The only thing I have in this calendar and never had before is the CATEGORIES field.
Is it possible that this is somehow not supported or causing issues? If so, is it with icsx or with the calendar apps? But then it is not only a single calendar app issue but multiple...

Thank you very much in having a look!

[odin568]

Adding another event to the category "TEST" afterwards is again correctly displayed. Thereby should be definitely an issue with different categories...

[odin568]

Edit: This post was wrong. Happens in google play version as well as standard version with two phones

[odin568]

I ran the ics through https://github.com/darkphnx/ical-filter-proxy without modifications. But it gets parsed and spooled out again.
It misses the timeszone definitions at the end completly, but now it works fine.
Categories are still in there, so seem not to be the issue but the timezone perhaps? But don't see an issue...