Reassign device to other user

Hi,
I need some help here.
I want to reassign a mobile device to another user, but I just can't figure out how to do it.
The user currently owning the device is my first Admin user of twingate. But he has a deprecated email address (which I can't change in Twingate), so I set up a new Admin User and want to have him as the owner of the mobile device. I am using github as authentication provider
I did:
- Archive the device from the current owner (deleting is not possible).
- revoked TOTP of the primary user
- revoked Github authorization for Twingate
- uninstalled Twingate app on mobile device
- send invitation link to new admin user
- logged out with primary admin user from twingate.

When I now use the invitation link for the new user from my mobile I choose github again as authentication provider and need to setup a new MFA for Twingate and after authenticating I get logged in. But as the old, primary admin user again ...
Any hints?

Thanks!