Touchback not working with USB-C display (Surface Hub 2S)

cezarcretu Actually, after so much testing on complicated scenarios, I have just discovered that Touch-back is simply not working at all.

I always had the USB-C plugged when using Miracast, so I thought that's how I was getting pen & touchback, but I just didn't know Miracast could do that without USB.

So in the end, I'll sum up my issue by:

1. Touchback Host seems properly installed on the Hub2S (tried removing it and enabling it again)
2. Touchback Guest properly installs on a wide array of devices, but only when using the Compute Module USB-C (none of the other ports react)
3. There is no touch nor pen input no matter how I connect those devices. Tried :
   1. Both with the USB-C single cable and with HDMI display + USB-C for touchback on the compute module).
   2. A Surface Pro 7 on W10 1903, Lenovo T490S on 1909, and Intel NUK 10th gen on 2004
   3. A total of 3 different USB-C cables of the right spec.

I'd guess there are only three possibilities left:

1. There is an issue with both of the Hubs we got.
2. Our IT guys applied some Group Policy which is blocking the touch functionality (probably unintended)
3. The hub is missing some driver updates that might not be delivered because of WSUS policy)

I'd love to know if there is an easy way to find out the cause.