Have you tried the new v2901 bios with the latest chipset drivers from AMD and an up to date windows 10? If it still doesnt work, then it may be a good idea to stick with the bios version that works for you right now and wait for Combo PI 1.0.0.4 bios to be available for your board (should be available for B450/x470 in a week or two) as ive heard of some simillar case as yours but it was with the MSI B450/x470 Max boards and they said that updating to 1.0.0.4 fixed all the issues they were having, its just taking some time for it to be available for boards like yours due to the limited ROM size of the non max B450/x470.
Also if your not seeing the problem pop up with 2605 but have it with all the other newer bios versions then the problem is most likely with the boards Bios and not the processor, which means its probably best to ask for help in Asus ROG forums as some users of the same boards as yours may have encountered the same problems you are having and may know of some fixes for you to try.