Hello @NJDrew ,Welcome back to the forums!
Switching accounts shouldn’t cause this issue. I just tested logging out and into a different account, and all my engines and projects still showed up correctly.
In this post, a solution is mentioned for the error you’re experiencing—it might work for you and save you from having to set everything up manually. They may have a better solution for your specific case.
If that doesn’t help, I’d recommend contacting Epic support before going the manual route.
If not, then unfortunately you might need to reinstall everything and rebuild your projects, including reinstalling the engines and plugins.
Hope it helps