PIC 18LF4431 RX not receiving.

Hi,
I have had two PICs talking to each other TX RX, via HC-12 radio modules. 18LF4520 to 18LF2431. I've now changed the RX PIC to 18LF4431. Programmed using Oshonsoft.

Here is the TX LOOP (MAIN):
main:
If button = 1 Then 'BUTTON NOT PRESSED
rled = 0
yled = 1
Hserout "$0", CrLf
waitms 100
Endif
If button = 0 Then 'BUTTON PRESSED
rled = 1
yled = 0
Hserout "$1", CrLf
waitms 100
Endif
Goto main

This is being received by a third HC-12 USB serial input to a Terminal ok....

PIC 18LF4431 RX not receiving.