4k60 intel uhd and the HP G5 Dock usbc displayport alt mode

[chazzy2501]

ok this one is in the weeds...

 

so to start:

 

I have a new 11th Gen i5 HP ProBook 440 G8 laptop with Iris XE graphics. This plugged into the G5 docking station (usbc) will in turn output 4k60 to the new interactive tv just fine, no changes or issues. This proves that the laptop, the dock, the hdmi cable (from dock to tv) and the TV can all handle 4k60...

 

Now the 10th Gen i5 HP ProBook 440 G7 with UHD graphics by default can only manage 4k30. BUT this is by default. In the BIOS you can bump the DisplayPort capabilities using a high-resolution mode. This mode will sacrifice USB speeds to just 2.0 (on the dock) but will allow higher resolutions. This would be great but when outputting 4k60 to the tv the image is black...

 

So to be clear it seems to be sending a 4k60 signal, it's just black...

 

These tests are with the same equipment, in the same room.

 

Ideas?