Docker container not saving settings all of a sudden

It's really not my day today. I've had Docker running for a good few months without any issues with data in containers being saved persistently through reboots and what not, until today.
Had some unrelated issues (in a different thread) and rebooted my NAS and the settings for the container are no longer saved and it has reset back to its default settings.
Any idea what's going on here? I did notice there were some docker updates and I guess maybe this somehow affected things, even though they shouldn't have.