Chipkit Uno32 Debug with mplabx
In order to use the debugger the debugging signals must be configured to communicate on the correct PGEC / PGED pair of pins.  It's hard to find in the chipKIT Uno32 manual which pins are used for the programmer header, but it is a little easier referring to the schematic.

From that schematic we can see that the programming header uses pins RB6 and RB7.  Looking at the data sheet for the PIC32MX320F128H chip those pins are PGEC2 and PGED2.

However, in your configuration, you have:

# pragma config = ICESEL ICS_PGx1 / / ICE / ICD Comm Channel Select


That will be attempting to communicate on PGEC1 and PGED1, which are pins RB0 and RB1.

If you change that to:

# pragma config = ICESEL ICS_PGx2 / / ICE / ICD Comm Channel Select


then you should find that debugging works.