Just had a weird issue - resolved with a reboot, but was very scary - posting here in case anyone else saw the same and needs a sanity check or solution.
Woke up today, saw there was an UD update, and installed the update. An hour later, my server is reporting that it can't find my license key, or anything else on /boot - everything throwing FAT read errors for /boot and sda1. Remounting the USB drive didn't do anything.
After some investigation - I see that UD has taken over the usb key and re-identified it as /dev/sdw - no idea why. I no longer had a /dev/sda or /dev/sda1. They simply did not exist anymore.
Rebooting resolved the issue - but my understanding is this should never have happened in the first place - I have the auto-mount USB devices option disabled, and no actual hardware changes were made - this appears to exclusively be the result of me installing the latest UD plugin.
I'd offer to share logs but they've rolled over and don't have anything useful. Hopefully this was a one-off...