Sounds like either a kernel bug or a kernel feature whereby it detects which modes the attached cable actually provides enough bandwidth for, and removes the modes that probably can't be sustained reliably.
If it is just a bandwidth problem then replacing the display cable might fix it.
Sounds like either a kernel bug or a kernel feature whereby it detects which modes the attached cable actually provides enough bandwidth for, and removes the modes that probably can't be sustained reliably.
If it is just a bandwidth problem then replacing the display cable might fix it.