Okay, but thanks for the detailed help. My predecessor probably messed up a bit
We have other 2016 problem servers, I think these also need to be set up again
Yes absolutely, and I reproduced the same issue on a VM and wasn't able restore it either! So the the only option left is re-installing this server from scratch.
You're welcome and glad I could help with the other servers. This is odd issue with an borked MBR > GPT conversion, it would have been better if a backup had been restored at that point...
yes and the problem is that there is a critical system running on this server. I can always restart it, but if something goes wrong by rebuild the Server I have a problem.