[werk_ag]

Hi Werk,

Can you just confirm, you want line 56 of the RX routines commented:
 

Code:

  if (TX_Relay_ID != Relay_ID || PacketID < 127) return;

It makes sense, vs the other line 56's in the code in other tabs. Hard to see how commenting out the library for the BME280 would help 

Yes, is that line. Sorry for having forgot to mention line 56 in RX tab.

I'm making some progress here.
The wireless display board is not showing actual values, but the green circle in upper left is flashing in synchronicity with the TX led from the TX board, and I am seeing values like this output on serial monitor:
 

Code:

10:01:50.928 -> 10:01:50 - Station ID: A1 PacketID: 3 Full Message: A10003 C8 0 0 0

So I'm guessing it is the RX module on the receiver that is the issue.

Indeed the TX unit is sending data. At least, you should had saw messages with PacketID 0, PacketID 2 and PacketID 3.

Based on this, I also guess that the issue may be the receiver module. Fortunately you said that have a spare RX module.
Before replacing the module, you may also check if there is continuity between the two points marked on the image with an arrow.