I have the same issue with the latest rhrexboot, the system is hung after showing 100% with the message "environment is loading into memory", my laptop is Lenovo T460P, but with the old image "rhrexboot-2020-08" it's working, and I checked compatibly with it everything works well, my exam will be next week please confirm to make sure if this image still valid and I can use it with my Exam EX200.
Same here... old an new image is not working with my HP Elitebook 845 G8. The second notebook from lenovo has also the same issue.
Error new image: stuck at 100%
Error old image: I see the 3 dots, then the graphic would not load.
It's sad, that there are that many problems.
Was there any progress for you? I'm stuck with the same problem just using my private PC. Nothing special about it - got full rights and everything. Was also trying it with several MacBooks and an Lenovo Laptop. Still not working...