Brent as usual is correct, however for everyone else's future troubleshooting issues.

The issue may still be with the cable. You notated its an MHY cable, which if I recall (and based on a quick google search) is a 'thin line' shallow head cable design which have bandwidth issues...on a similar note, none of the 'thin line' type cables should be used going forward for anything 4k and/or runs greater than 6ft as they have current drop and termination issues that often cause problems (as well as easily broken conductors which may or may not be visibly damaged).