Neither e-mail nor notification reminders are saved in calendar events (NC 31, Calendar 5.3.5)

Steps to reproduce

1. Open Nextcloud Calendar
2. Create a new event (or edit an existing one)
3. Add a reminder (e.g. Notification – 30 minutes before or E-mail – 30 minutes before)
4. Save the event
5. Reopen the same event

Expected behavior

The selected reminder(s) should remain saved and visible when reopening the event, and should trigger at the configured time.

Actual behavior

• Reminder settings are not saved
• Reopening the event shows no reminders configured
• No notification or email is triggered

Calendar app version

5.3.5

CalDAV-clients used

No response

Browser

No response

Client operating system

No response

Server operating system

No response

Web server

None

Database engine version

None

PHP engine version

None

Nextcloud version

31.0.10

Updated from an older installed version or fresh install

None

List of activated apps

Nextcloud configuration

Web server error log

Log file

Browser log

Additional info

No response

Start by reproducing the reminder save and reopen steps in Nextcloud Calendar 5.3.5 on Nextcloud 31.0.10, checking both notification and e-mail reminders. No files or tests are named, so trace the event persistence and reminder handling from the reproduced failure. Done means reminders remain visible after reopening and trigger at the configured time.