Henrik, have you pinged Charles Leo about these issues?
No, not this time, but have done previously - several times actually (see here, for example). Apparently others have been able to make it work (with some specific, previous, version of MPLAB) but I'm not smart enough to figure it out.

Hopefully they can put together an install MOP/Manual to get 3.0.8 working for all of us with the correct version of MPLABX with the functions we need working.
One would think so but, like I said, have been asking for years. First time was when MPLABX 1.0 was released back in 2011/2012.

Anyway, since I haven't been able to make it work I haven't actually TRIED MPLABX. Perhaps it's not as usefull as an IDE as I hope it is and there are others IDEs available but I REALLY want to be able to use source level debugging, at the hardware level, and as far as I know you can't do that with anything else. I've been publicly wishing for it to be integrated into MCSPX but it probably won't happen.

/Henrik.