B650M-CX R2.0 USB device causes boot hang

I have had a few older USB devices cause issues like this. It's almost always
a compatibility issue with the old device. In some cases enabling CSM in the BIOS
allows the system to POST normally but CSM needs to be disabled for secure boot so
that isn't really an option.

In the case of the few devices I have with the same issue I am able to plug them
back in once the system has booted and they work just fine. I have 2 devices
connected to a USB hub so I just have to connect and disconnect a single USB
cable. My problematic devices are an a wireless mouse dongle (USB 2.0) and
a USB C microphone (Sennheiser). I have a few USB flash drives that cause the
same issue too. Ultimately, USB standards are often not followed properly and
newer boards, AM5on AMD and LGA 1200 and newer on intel can be much pickier with
some USB devices. Safe boot and TPM 2.0 have made the issue much more apparent
as they require CSM mode to be disabled to function.

With a lot of messing around and trying different motherboards I was able to get
my USB C mic to work but not most of the other problem devices I have. In the
end I just went with a USB hub that I can disconnect at boot then reconnect
once the OS is loaded. I connect all my problem devices to that to avoid boot issues.

I am sure this isn't what you want to hear but it is pretty much the best solution.
Effected devices all have firmware of some kind and the system attempts to communicate
during POST. Any out of spec code in the firmware causes an issue. Even my USB
c 3.2 microphone has an issue with this. It comes down to security changes made
more recently to support safe boot etc.

FYI, CSM mode contains USB legacy device support, that is why there is no separate
option. CSM = Compatibility Support Module. It was great for supporting old hardware
and in the past was enabled by default. Since safe boot became mandatory for
windows installation it has been set to disabled by default. I see issues like
yours pop up all the time ever since. It isn't a board or BIOS problem, it's
bad adherence to USB standards on some older devices (and some new ones too).