Hi @jmangan,
Although I’m not exactly sure of what’s happening, I might have a couple of hopefully helpful pointers for you.
We’ve recently had a user report an issue with Duplicati backups and its RAM usage, for which I’ve found several other reports online from general Duplicati users. My first thought would thus be to have a look at your memory usage and checked whether or not you can see your swap space being filled up when Duplicati runs its backup(s). That might explain why it leads your machine to crash. See the post linked below for details:
That one is curious, especially given we just had another report of something very similar by @gburian; see their post below:
In your case, I’m not sure why your share is shown as unmounted, unfortunately, but I would recommend to run the various btrfs commands I listed in this thread as they may bring more information on your system’s pool/share situation. Would you happen to to have run any update(s) or disk operation (adding/removing a disk, for instance) recently?