Thanks for your reply. No, the triangle didn't go away after restarting the software (and the PC), nor launching manuall.y.
However - I have now changed the motherboard as I was experiencing other issues and this problem appears to have gone away now.
The new spec of my system is; (I ditched the Gigabyte Aorus motherboard for an MSI Z790)
MSI Z790 Gaming Pro WiFi Motherboard
Intel Core i9 13900F (Socket LGA 1700) 3.0GHz 24 Core CPU
Corsair Vengeance 32Gb DDR5 RGB 6GHz
Gigabyte Nvidia RTX4090 OC 24GB Triple Fan
Cooler Master Gold 1250W Power Supply
Cooler Master MasterLiquid ML360 Illusion Water AIO
Antec Performance 1 Case
Windows 11 Pro