A3000 31KHz video on LCD problem / questions...

[Zac67]

The LCD monitor I'm using supports the following input frequencies: 30 to 63 kHz horizontal; 56 to 76 Hz vertical - could this be the issue?

Obviously 50 Hz PAL is out of range - try NTSC 60 Hz.
You can default to NTSC by moving J200 to 1-2.