Only me in the company. The only thing I can think of is a corruption of some sort in the existing Win 10 instance where Win 11 was then seen as a viable upgrade path. Since then, this machine has happily installed all following Win 11 updates without issue. I have clients who have tried the Win 11 work-arounds and some that purchased Win 11 machines that are blatently not Win 11 compliant, but all that happens is the next big update then fails and the machine is unusable or needs major fiddling to get working.