Only reason I can think that disabling the monitor in the Device Manager is that it disabled freesync or HDR or stops windows trying to send CEC power saving commands or whatever.
I have no idea why it's a fix, but it clearly stopping windows from trying to do something which causes the screen to flash.
I would be surprised if changing between limited and full-range fixed it. That's a hangover from old broadcast standards. It doesn't change the data rates.
It seems like it's working at lower data rates?
So 1440p60 is working but 1440p144 isn't?
Which points to an HDMI cable issue, a GPU issue or a GPU driver issue (and I mention GPU/Driver because of freesync)