Automatic Backups Not Working in Linux Mint

[pvstyps]

I've been using the Simple Backup plugin with Joplin for a while now on two different machines and it's been working great. I just added Joplin 2.11.11 to a third machine running Linux Mint 21.1 and the automatic backups don't seem to be working in this case. Manual backups do seem to work just fine, however. I've tried deleting and reinstalling the plugin but that didn't change anything, and I've also rebooted the computer and application several times and waited for a long time to see if an automatic backup would eventually be created, but nothing seems to work.