Not sure how much help I can be as I don't have a PICkit3, have never
used a PIC18F45k20 and I normally program in C and use an ICD3 for
debugging.

That said, you program is short and has no loop so it will execute
instantly then run wild in the random flash.

try putting the code in a loop and then setting a break point before
executing it.
You should then be able to step through the code.
That is assuming that the  PIC18F45k20 is able to be debugged by a
PICKit3, I don't know if it is, you would have to refer to the
Debugger Documentation to see if it is a supported device.
--=20
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