American Megatrends BIOS boot problem

I have a Gigabyte Z390 UD motherboard with the latest BIOS (F10) installed. Whenever I perform a soft reboot, or about half the time when I do a hard reboot, I get this issue. The Logo and details comes up, then about 5 seconds in, it starts flashing as if it were refreshing the screen. It flashes for about 10 seconds and then drops into the BIOS setup screen. Any ideas what the issue is and how to fix it? I&tried numerous settings inside BIOS and nothing I&tried has seemed to make a difference.