The last few days I was working with installing Big Sur on my 5,1 cMP, using OpenCore and an EFI boot. Long story short I decided to stick with Mojave, but now the machine always boots very slowly from a black screen with the Apple logo, and if I have to go to the Startup Mgr, it doesn't give me the usual gray screen with every volume. I've tried resetting SMC and VRAM; even reinstalled Mojave - no change. Any way to get this back to normal?