I get lines like this in my Xcode console about 60 times per second: 2022-03-25 00:11:16.667813-0700 MyApp[22325:1916761] [] CurrentVBLDelta returned 0 for display 5 -- ignoring unreasonable value 2022-03-25 00:11:16.668092-0700 MyApp[22325:1916761] [] [0x7f82f48a2a20] Bad CurrentVBLDelta for display 5 is zero. defaulting to 60Hz. This is apparently a new bug in CVDisplayLink or connected code. I'm running Monterrey 12.3 on a new MacBook Pro 14" driving an LG 27" Ultrafine monitor.

I went back to my old Intel MacBook (also Monterey) and there is no problem there (same JUCE project). I also verified that the M1 problem does not depend on using the external display (happens also when LG is unplugged and only using the MacBook Pro screen). Building for native ("My Mac") instead of Rosetta gets around this problem, but then I have others related to audio which I won't belabor here. Nice that this one seems to be a Rosetta-only problem. Back to Intel hardware it is for me for now . . .