@thorr - I'm sorry, I didn't realize you meant to look for the volatile framebuffer setting on the MiSTer itself. I was looking in the .ini/mame settings menu. You said core and I seem to have overlooked that key word. This was definitely just me pulling a stupid!
The volatile framebuffer setting was set to on, so I toggled it, but I still get a black screen. Everything seems to be working in the regard that I have the bouncing ball screen going and it disappears when I start MAME, so I'm going to assume the VGA/CRT isn't receiving the right settings. The MiSTer core settings are still very much available on screen though, so it's good to know it didn't freeze or anything.
If my PC is directly connected to the MiSTer via Anker USB-C Ethernet dongle, should I be messing around with subnet mask on the Windows side? Something tells me no since MiSTer is clearly getting some sort of feedback from the PC already. Also, is there a comprehensive list of available monitor options I can swap out in the mame.ini? A cursory search brings back a few different results, but they don't seem too terribly up-to-date.
This may or may not be related - when I try to run MiSTerCast, I receive an error on open:
DxgiOutput1->DuplicateOutput failed: -2005270524
Failed to initialize video capture.
As far as I know, both MAME and MiSTerCast are whitelisted in my firewall settings. And if that isn't enough, I am now also noticing that I am no longer able to wirelessly FTP into the MiSTer if there is a static IP assigned to the MiSTer Ethernet port. Update_all displays "name server cannot be used: temporary failure in name resolution, unable to sync." Once I remove the static IP on Ethernet, the wireless side works again. 0_o
EDIT
I ran dual displays from the MiSTer to see if it was just the VGA CRT not receiving the correct signal, but the 2nd HDMI display also displayed black. I'm officially at a loss as to what's going on.