z690 Steel Legend IGPU Multi-Monitor not working

I recently built a new rig using the z690 Steel Legend WiFi 6e/D5 and Intel Core I7 12700 CPU. I have a BioStar RX 560 4GB 128-bit DDR5 GPU installed and connected to a Dell P2314 23" monitor via DVI. I also have a Dell P2210 22" monitor connected to the IGPU Displayport via a passive DP to DVI adapter. Trying to setup dual monitor, I am getting output on the P2314 from the RX 560 but nothing from the IGPU on the P2210. I have IGPU Multi-Monitor enabled in the UEFI and tried shared memory set at Auto and 1024MB, both without success. Any help with this would be greatly appreciated.

IXer0 wrote: Oh, I forgot to include my UEFI version: 4.03

Update: Ok, so I updated the UEFI to the latest(v 9.03). This seemed to fix the problem. some additional options are now available: under Chipset Configuration, there is now an option to select the Primary Graphics Adapter. regardless of whether I select "onboard" or "PCIE2", as long as IGPU Multi-Monitor is enabled, both the discrete GPU and the IGPU are operational, which unsuccessfully, I was trying to achieve before the UEFI update. so problem solved.

the only problem now is that I cant seem to boot in legacy mode. on the "Boot" tab, it says that CSM is disabled and to enable it I need to install an external graphics card. WHAT?!?! But I have a graphics card installed! so what does this mean? Another bug?

Any insight would be appreciated, as I wish to be able to boot both UEFI and Legacy OSes and utilities, as was possible before the UEFI update. Thanks in advance for any responses.