I've tried changing hdmi_safe to 1 in the conf. All I get is no signal on a 4k ultrawide. It is interesting that my monitor will have been running for some time with a black screen, and a bit after I turn on the Pi it will pop up with 'No Signal.' So it seem slike it's making some sort of attempt, maybe??
The green light is active for some time with rapid blinking with the SD card in, but eventually it justs stays red (sleeping?). Without the SD card it stays green for a few moments, and then proceeds to blip on a few times followed by a pause, followed by more blips and pauses.
Not sure what else to try! The wiki seems to state that hdmi boost doesn't do anything on the raspberry pi 4. Any ideas?
edit: title says no input, but it's no signal - not that it makes a difference