today I had the problem again and I could analyze it a bit more. Here is what I found out…
It is no connection problem. I can replicate the problem with Wifi connection.
In my case only one file is affected. There are 15 files in the folder right now, and I can modify every file and it get synchronized correctly, except one file. The files are all identical Excel templates and differ only by the file name and contents of the tables. If I copy the file, which has sync problems, the new file gets synced without problems.
In the Seafile app you can see the filename and beneath it, you can see the file size and also a time stamp that shows when the file was modified for the last time. If u modify a file in the app, save it and go back into the seafile app, you usually get a short popup: “updated filename” (deutsch: “Aktualisiert Dateiname”) and the time stamp gets updated. That doesn’t happen to the affected file.
You can open and save the file again, but the timestamp gets no update and no popup appears. As long as you open the file with the same Android device, it contains the correct data, but it doesn’t get synced with the server. If you now open the file with another device (in my case a desktop client), the data is lost (also on the Android client) and the file now contains the data that it had, at the time of the old timestamp that is displayed (rollback).
If I modify an affected file and rename it in the seafile mobile app, it gets synced containing the “old time stamp data” (rollback).
After much trial and error and some breaks, the seafile android app synced the data of the affected file. Some minutes later I added Data to a table, saved the file and again it doesn’t get synced.