Hi, This is an old bug in libpam-systemd which maintainers still refuse to acknowledge (and upstream refuses to consider it a bug). Unfortunately, mate-settings-daemon is just another victim of it. It's at a level below us and we can't fix it ourselves.
If you know how to patch Debian packages, you can try to patch libpam-systemd with the patch from [1]. If you don't know how, I recommend reading an excellent article about it [2]. [1] https://github.com/linuxmint/systemd-betsy/commit/f7ab85f1e1169ac1598dfc1fba1c01063840b3c5.patch [2] https://raphaelhertzog.com/2011/07/04/how-to-prepare-patches-for-debian-packages/
