can't get save secure boot variables to work with x-570a pro

[seanmcd2164c02f7]

i have an x570-a pro motherboard running 7C37vHH from 2022-05-<something>. this version is no longer in the download list.
i am running in uefi mode with secure boot enabled. this has been working for several years.
i am trying to upgrade the cpu. but, of course the system won't boot because the new cpu doesn't have the secure boot keys from the old cpu.
this is what i expect and seems to be working correctly.
if i go back to the old cpu everything works fine again as expected and the OS continues to successfully boot.
if i reboot into uefi mode, set secure boot to custom, go to key management, select save all secure boot variables the screen goes grey and nothing happens.
if i go to each secure variable in the list and click save to file nothing happens
i expect either of these things to use the only usb stick plugged into the machine since this is how firmware upgrade has always worked.
but no data is ever written to usb.

where is the data supposed to get saved?

how do i backup and restore my secure boot variables so i don't brick my OS install?

i have hunted all over the net with multiple search engines for directions for this for a couple of hours and all i can find are directions for enabling or disabling secure boot.
i already know how to do those and they aren't what i need.

thanks

 

[citay]

How about updating your BIOS to the latest version first? It's no good fiddling around with an old version which might have bugs related to your problem. You update the BIOS first, to avoid the risk of all your troubleshooting being a complete waste of time, should a buggy BIOS cause all your trouble.

The version not being listed anymore also isn't a good sign, usually the pulled it then, due to a bug that was deemed too severe.