Ok, so my dream of using PBP3, MPLAB X and PICKIT4 are not extinguished ... yet.
mplabx is not a viable ide for pbp3. its useful to get mpasm and the mplab ipe only for mcs use.
if you want to use it as an ide for pbp3 then use ver 2.35 or older , none of which will allow use a pk4 of course

or use xc8 "C" with latest mplabx