Lenovo laptop hdmi, Windows 11 no display on dummy plug but ok on external monitor?

Hello,

Got a weird situation.

Until now, i've been using fake monitor dummy plugs on vga/dvi/hdmi/displayport with Windows 10/11 successfully on PC/laptops, along with CRU utility.

I've got a Lenovo P1 G7 laptop which has built-in HDMI 2.1 connection. I tried both hdmi 2.0 and 2.1 dummy plugs on it, and Windows 11 does not detect a new display. Perhaps a bad hdmi port on the laptop? I connected up a hdmi external display, and i get new display. Maybe the dummy plugs are bad? I tried them in different laptop/PC combination, and each show the new displays in Windows 11.

What's going on here?

I connected up the port replicator, which has hdmi port on it, to the laptop. Plugged in the same dummy plug, and Windows 11 shows new display.

Seems from isolation that this Lenovo P1 G7 laptop's built-in hdmi, is good, but hdmi dummy plug will not work (for some reason). Well, this is first failure for me in such situation.

Anyone run into compatibility issue on a particular laptop hdmi port with hdmi dummy plug that is known good and works in other latop/PC's hdmi 2.0/2.1 ports?

What could be so unique about the Lenovo P1 G7's hdmi port?


Here the hdmi external display is connected to the laptop's hdmi port (i do have connected to laptop, two dummy DisplayPort's, total of 4 displays, 1, 2, 3 and 4)



Unplugged the external hdmi display, plugged in hdmi dummy plug. Windows 11 does not detect the new display. Windows 11 only has displays 1, 2 and 3.




Thanks!