Appointment status isn't synced from Nextcloud Calendar

[cdhermann]

Under certain circumstances appointments aren't synced from the Nextcloud instance to the Android phone.

Prerequisites:

• Nextcloud AIO installation with the Nextcloud calendar (https://github.com/nextcloud/calendar)
• At least two accounts (called here A and B) in the Nextcloud installation
• Thunderbird subscribed to the calender of B
• Account B has an Android phone with syncing the Nextcloud calendar enabled via Davx5

Steps to reproduce:

1. Account A creates an appointment in the Nextcloud calender web interface
2. Account A invites account B to the appointment
3. Account B sees the appointment in the Thunderbird calendar
4. Account B accepts the appoint with the Thunderbird UI control "Accept"
5. Account B sees the appointment to be accepted in the Thunderbird UI as well as in the Nextcloud web UI
6. Account B starts a sync (or waits for the scheduled sync)
7. Account B doesn't see the appointment as an accepted appointment on the Android device
8. Account A sees in the Nextcloud web UI that account A has accepted the appointment invitation

Does anybody else have this issue?