For some reason systemd/journald (?) stops writing the logs afzer a while. Accordingly, no recent logs are found and journalctl -f does render no results.

This different from the behaviour under 3.4 on the XA2 and the Xperia 10.

After a reboot, there is log for about two or three hours and then.the logging stops.

I was investigating the behaviour when a USB device is connected to the XZ3. That is why I used journalctl and found the strange behaviour