The handler "type" needs to be PBP.
Otherwise, PBP's system variables get corrupted and the main loop get's lost.

Code:
ASM
INT_LIST  macro    ; IntSource,    Label,  Type, ResetFlag?
       INT_Handler    RX_INT,     _IntRx,  PBP,    yes
       INT_Handler    INT_INT,    _IntBt,  PBP,    yes        
   endm
   INT_CREATE               
ENDASM
  @ INT_ENABLE   RX_INT
  @ INT_ENABLE   INT_INT