Ah, thanks! I was already running 8.0.5, but the upgrade to 8.0.6 got stuck. /home/yellowtent/box/setup/start.sh came up with an unbound error. I was able to start box manually and start all apps, but the backup volume did not mount. After installing unbound-anchor, I was able to run /home/yellowtent/box/setup/start.sh without errors, and now the backup is working again.