package: mate-screensaver version: 1.22.1-2 I see this in the journal Aug 17 08:35:13 debian-laptop systemd-logind[813]: Delay lock is active (UID 1000/bw, PID 3508/mate-screensave) but inhibitor timeout is reached.
Going back to 1.22.1-1 solves the problem for me.