Failed to upload to backblaze - stuck locking local path

I’m trying to sync my Truenas Scale system with backblaze B2, this was previously working, however recently all of the cloud sync tasks to Backblaze keep getting stuck on “Locking local path ‘/mnt/Euler’ for reading”. This also happens with my google photos sync, however the google drive sync completes successfuly. These backups were working until recently however I am not sure what has changed to result in these issues.

I have checked to confirm the details are still valid and the server can access the internet properly so I’m not sure what might be causing this.

Any ideas?