Have you tried changing Windows display settings 'Make this my main display' to the monitor connected to the 5600 ?
CSM disabled in bios ?
Usual boot priority was vga > dvi > hdmi > dp.
Ryzen 5 5600x, B550 aorus pro ac, Hyper 212 black, 2 x 16gb F4-3600c16dgtzn kit, NM790 2TB, Nitro+RX6900XT, RM850, Win.10 Pro., LC27G55T..