TBT3-UDZ second HDMI port not working with 2020 HP Spectre X360 (Intel Iris Xe)

I’ve just come across this thread as am experiencing almost the identical issue. I’ve a new HP Spectre x360 with the 11th Gen chipset just like the first poster – Model 14-ea0018tu. And just received today the TBT3-UDZ dock which I’m using with two identical BenQ monitors via HDMI, but one of the monitors continually and randomly flashes on and off and it is related to being connected to the HDMI port 2 (upper port) on the dock as I can replicate the issue by swapping cables so it isn’t a specific monitor or cable issue. I’ve an older HP Spectre x360 laptop (8th generation) and it works fine with the dock and monitor setup so certainly seems to agree with the thread above that is related to the new HP graphics or Bios set up? My Bios version is F.09. Any further information that I can provide and advice you can give to help resolve this? Many thanks. Tim

Edit: So an update to this. I managed to seek out the original F.07 Bios and was surprised that I could install this without issue and yet, the flashing monitor is still happening…