Phantom account appears whenever creating new cloud build project

We had been using Unity Personal Edition and the free version of Cloud Build but have recently upgraded to Unity Pro and the activated the 12-months of Cloud Build Pro.

Prior to the upgrade, one of our team members changed the email address on his account to use our organisation email ( @risegames.com) rather than his personal email address. He had been added to the Rise Games organisation in Unity prior to the change, and his email address seemed to update fine.

When I created the cloud build project for our game his old personal email address was added as a collaborator automatically, even though we were using the free plan and should not have any collaborators. He couldn't log in to cloud build with either account, or even manage his account settings.

Since upgrading to Pro, the phantom personal email address keeps appearing as a collaborator on any project we create. Also, he is not able to install any cloud builds, it just hangs on a blank screen whenever he tries to access any cloud build link (even to manage his account). This happens on all devices and browsers, desktop as well as mobile.

As it stands, we cannot use cloud build to distribute builds, which is obviously causing some frustration! His attempts to contact Unity support have led to no resolution to date. Any help is appreciated.