Big Sur - USB keyboard (and mouse) not recognised

I've managed to boot into the Big Sur installer on both my Optiplex 380 via OpenCore (see this thread) and on my Mac Pro 3,1 - however in both cases the keyboard and mouse don't respond and I can't progress any further than the language selection screen. On further inspection, there's no signal going to the keyboard as pressing Caps Lock doesn't turn the light on.

I thought the problem...

Read more