RobotStudio 2020.4 not working

cpvicent Barrie, Ontario
Just updated to RS2020.4.
Now when I open an existing station the program goes into an endless loop of building collision sets even though there are no collision sets active!
Then it takes forever to start the robot VC. 
I previously had RS2020.3 and it was working flawless.
I there a fix for this?
How can I revert back to 2020.3?