Wanted to add my 5 cents.
I had a different grabber that did't have the pin 13 connection. Used the extra PCBs with PIN13 jumper cable connection and my TV always switched HDMI channels when CEC connected. So something with that grabber and my TV didn't work.
So I bought the same grabber as yours. (at least on the picture)
The PCB Layout again is different and Pin13 are not connected at all on either of the HDMI Ports.
I still had those extra PCBs, so I tried out the jumper cable connection again.
now it's working!!
Hyperion and CEC parallel.
Thx for all your help.