Out of interest did you remember to create a volume for the /home/node/.n8n folder? I am just wondering if the data is being wiped and the image is being recreated.
Correct, in this case you would use the default which is SQLite.
I would assume the same as @Jon or that you restore the data in a docker container that has a different folder, or no folder mounted. Meaning those credentials and workflows get restored in a totally different database than the one you are accessing.