Comment 13 for bug 1946525

It's a strange one. I appear to have had this as well. The output from dmesg shows it detects the drive just fine. It also appears in Nautilus, which will mount it for you when you click on it, but that's obviously a complete no-go.

What fixed it for me was simply reinstalling the fuse package:

sudo apt install --reinstall fuse

and rebooting, as per the advice here https://askubuntu.com/questions/1361627/ubuntu-mate-21-04-usb-stick-will-not-automount which I know isn't 21.10, but worked for me regardless. No clue why it went wrong in the first place, but at least I've got it sorted for now.