Another interesting test is after the PC has failed to get the correct edid, toggle the HPA line to force the PC to re-read the edid and see if it comes in clean. This thread shows how to do it
https://ez.analog.com/message/52926#52926
The registers are the same for the 7611 and 7619
Another way to toggle the HPA line is, if it has a 10k pullup to DDC_5V then you can just tap a 220 Ohm resistor from HPA to ground. This will glitch HPA causing the PC to re-read the source.
