Due to the CODEGRIP specifics, a portion of the RAM memory must be reserved for its functioning during the debugging session. This memory portion is set in the RAM Ranges input box in Project Properties -> Compiler Global Options -> Linker -> Memory Model window :



For PIC18F45K22, this portion is located in the 0x50-0x51  address range, so you should enter -50-51 (omit 0x and place minus sign at the beginning).

The amount of RAM memory that needs to reserved for a specific MCU is presented in the following tables :

PIC12

PIC16

PIC18

PIC18FK

PIC18FJ