When programming my PIC18F6722 using MPLAB IDE v8.91 (the 32bit version), my PIC works and starts successfully, but when I use the HEX generated from MPLAB IDE, but program it using MPLAB X IPE, the programming part is successful, but my PIC does not start up.
Bug resolved. The issue was that MPLAB IPE was overwriting my configuration bits.. I only had to change the configuration bits in MPLAB IPE, to correspond to the ones already set in MPLAB IDE v8 (they were set via the code)
Comparing HEXs from both a successful PIC and a failed PIC told me that the issue was in the configuration bits (with the help of other people on the internet)