877A
Well that is what happens when you do not look at the attachments.

But on the transmitter part I still do not see ADCON1 = 7.
And on the receiver part I do not see CMCON = 7.

And in the schematic pin 3 of the LCD goes straight to ground. No pot for contrast. I know on some modules this works, but are you sure it is this time.

not much help.