Confirm BIOS/CPU Compatibility HP Elitedesk 705 G5 SFF

I'm trying to install a Ryzen 7 Pro 3700 into my 705 G5 SFF.  It's listed as compatible on the HP support document.  When installed the system won't even post.  Nothing on the display.  No typical HP Sure Start logo at normal boot.  Can't enter BIOS.  I have a discrete GPU already installed (HP Radeon RX 550X). CPU works in another brand motherboard (ASUS, don't remember the model). Everything works as it should with the Ryzen 5 Pro 3400G installed/reinstalled.  

So I want to confirm that it's compatible in the BIOS, and if not then have it added.

Thanks in advance.

latest BIOS from HP site:
https://ftp.hp.com/pub/softpaq/sp146001-...146118.exe