Android sync not working (WebDAV target and 150k items)

On this other topic: Fails to sync

@Herve5 proposed this:

(it's about checking and deleting eventual lock files in .lock folder)

I checked: my .lock folder is empty.

I tried the Android sync again after deleting the data from the Android application to start from scratch: same problem, the arrows rotate and the message "Cancel" is displayed, which indicates that the sync is in progress, then the arrows stop running and the application is frozen.

Do you have an idea of ​​the problem @laurent and @personalizedrefriger?

I think I can live without the Android application but if there is just a small problem it would still be a plus to have it