Problem scope

• I'm sure that this is a DAVx⁵ problem.

App version

• I'm using the latest available DAVx⁵ version.

Android version and device/firmware type

Pixel 7a, Android 15

Steps to reproduce

Description:
I am using DAVx5 to connect to a Nextcloud server that has the nc_ext_dav_push app installed. Both calendar and address book sync correctly. I have enabled the ntfy push service and two different up* topics were automatically subscribed (I don't know why there are two).

When I change a calendar event, the Nextcloud server sends a POST to /upXXXXXXXXX?up=1 (one of the topics), which returns a 200 OK. I can also confirm the message was received by manually checking the topic. The message has the following format:

<?xml version="1.0"?>
<x1:push-message xmlns:x1="bitfire.at/webdav-push">
<x2:propstat xmlns:x2="DAV:">
<x2:prop xmlns:x2="DAV:">
<x1:topic xmlns:x1="bitfire.at/webdav-push">personal-1</x1:topic>
<x3:sync-token xmlns:x3="DAV">2998</x3:sync-token>
</x2:prop>
</x2:propstat>
</x1:push-message>

I believe the message is correctly received by the phone (other subscribed topics work fine, and there is no authentication required for up* topics). However, DAVx5 does not trigger a sync.

Question:
Why is DAVx5 not triggering a sync after receiving the push notification?

davx5: 4.4.10-ose (f-droid)
ntfy: 1.16.0 (f-droid)
NC: 31.0.5
nc_ext_dav_push: 0.0.2