Deployment Pipeline - Unable to deploy from Dev To Test (even no error thrown)

We have the same issue when trying to deploy from Test to Prod, even though both workspaces are in premium capacity.

Created a 2-step deployment pipeline yesterday by assigning one of our premium workspaces as a Production workspace. Then used the "Deploy to previous step"-feature to create a Test workspace, which got created as a premium workspace as well (labeled with the diamond). That all went fine, copied and synced from prodution to test within seconds. Today we published a new version of a dataset to Test, refreshed it and then clicked "Deploy to production". That has left us staring at the endless "Copying the content to this workspace" ever since. Refreshing the page brings us back to the screen showing that there are changes in Test not reflected in Production.