I had a similar problem with a PI4b and the Yamaha RX-475 receiver.
I solved it by changing some options in the config.txt (boot folder)
"hdmi_force_hotplug=1" did it for me.
You can also try :
Wait for x seconds in start.elf before loading kernel.
Wait for x milliseconds in start.elf before loading kernel.
Do those options work on the x86 image ?
Try this :