A/V Output NONE FOUND for FCPX [in 2020]

Okay, so I have a 2016 loaded 15" MacBook Pro on an LG 34" Ultrawide.

On FCPX, I was using the Ultrawide as my main monitor for timeline and workflow, and the MacBook screen as the viewer.

Down the road, I (initially) got a Sceptre 24" LED to add to the configuration... (dual monitors now, technically three if you include the source) and was using a 3rd party dock to output as follows:

• USB-C out from MacBook via 10gbps cable into USB-C of LG UltraWide
• USB-C out from MacBook via 10gbps cable to dock then to HDMI out, into HDMI of Sceptre

Everything worked fine, A/V Output showed up on FCP no problem. No issues here.

Hold on to that for a sec...

I then upgraded to a Philips 32" 2K, replacing the Sceptre, literally same output as previous setup, BUT now FCPX doesn't recognize the A/V Output, despite the monitor being fine in all other applications...

I tried changing to faster 40gbps cables and even tried variations of displayport/hdmi/thunderbolt/etc.

Why now is "none found" when it worked before and the monitor is the only thing that changed?

This is a photo of said setup.