This works fine on a 16F876A @20MHz with PBP v2.46. I changed the port
pins, and used true mode through a max232, but it works as expected. With
or without the character pacing.
Code:
'=====DEFINES=====================================
DEFINE OSC 20

'======Outputs====================================
DEFINE DEBUG_PACING 70 
DEFINE DEBUG_REG PORTC
DEFINE DEBUG_BIT 6 
DEFINE DEBUG_BAUD 115200
DEFINE DEBUG_MODE 0 ' 1 = inverted, 0 = true

'======Inputs=====================================
DEFINE DEBUGIN_PACING 70
DEFINE DEBUGIN_REG PORTC
DEFINE DEBUGIN_BIT 7 
DEFINE DEBUGIN_MODE 0 '1=inverted, 0=true

payload  var byte[15] 
reply  var byte
msg  con "~" 
timeout  con 5000 ' Note change from (timeout con byte)
reply = 5 ' receive 5 characters in payload string

Main: ' Display "Waiting..." every 5 seconds if timeout period expires
    DEBUGIN timeout, error, [WAIT(msg), Skip 13, STR payload\reply]
    Debug "Received: ", STR payload\reply,13,10
    Goto Main
    
Error:
    Debug "Waiting...",13,10
    goto Main
    
    End
Sending ~ABCDEFGHIJKLMNOPQR from MCS terminal to the PIC it displays;

Waiting...
Received: NOPQR ' ABCDEFGHIJKLM are skipped, NOPQR are received
Waiting...