I had a very similar issue trying to change which account was used to authenticate gitlab to our existing app and workflows. There was no clear solution to the problem but I basically tried these steps over and over, while also trying to run a workflow.
Remove the app from my personal gitlab profile
Remove the integration to gitlab from Users & Access
Add the integration from Users & Access with the new account (creating the app in gitlab)
In one of the workflows I had already configured, adding a new primary repository, which is just the same link
Make sure every workflow is using that "new" primary repository
Delete the old primary repository from the xcode cloud settings for my app
Eventually it worked, not really sure which one of those steps did it
Topic:
Developer Tools & Services
SubTopic:
Xcode Cloud
Tags: