So I checked the config for the external drive again and discovered when it was remounted it had added a, "1" to the end of the drive name. I went back into the .env and changed the library location to reflect this. Restarted docker and it is now connecting again. Obviously it is not ideal to be using a external HDD, but I wanted to test immich out for a while before investing into a bigger self hosting rig for all my services.
Ultimately problem solved though
Oh no, we'll have to use something other than terrible, AI ridden MS office? How terrible