Symptoms -
Faf client works fine, opens a lobby correctly when a game is joined, but I just get a big gray box when the game launches.

Resolution - (pun intended)
Digging into the log I found this -
warning: c:\work\rts\main\code\src\libs\gpggal\DeviceD3D9.cpp(866) Invalid call
info: SC_PrimaryAdapter 1600,1200,60

I realized I had swapped out my monitor for a new one. Opened up the game through "C:\ProgramData\FAForever\bin\ForgedAlliance.exe" and changed my screen resolution.