light out

Have you checked all through the trailer for a wall type switch? Even though there is a switch on the fixture, power may be controlled through a switch on a wall or on a cabinet.

If there is no wall switch and the blue wire has no power, I guess you're destined to pull 12V power from another location.

The light in question is central on the ceiling and is an LED with a switch on the light fixture (2 LED). The fixture has two wires which connect to two wires coming in from inside the ceiling. These two wires are NOT tied to the wires of the light fixtures fore and aft of the one that isn't working. I attempted to fish a wire across to either of these but the A/C unit obstructs the path forward and something (can't see what) obstructs the path aft.

The fuse box is towards the rear of the trailer. The fixture to the rear does have several other fixtures ganged on it but I am almost positive none are for the fixture in the center. The wires that feed these fixtures are BLACK (and of course the white ones). The positive wire that feeds the non-working fixture is BLUE (and of course there is also a corresponding white wire).

The wires head over to the microwave cabinet area and likely go over an a/c duct (plenty of room) but the microwave hole is all sealed up and no 12V wires are visible; they may be in the ceiling which is sealed over the cabinet. The blue and white feed wires have no looseness when pulled and nothing is ganged off these wires; they just connect to the non-working light fixture. I am not keen to start cutting holes above the microwave but....

There is a light fixture next to the microwave cabinet under a kitchen cabinet and all wires seem to go off in a run somewhere between the bottom of the cabinet and the finished inside of the cabinet in a sort of wood wire chase. The positive wire is black for this fixture.

Where should I go with this? The light isn't critical but it would be nice to have it working. TIA wg

Is that light controlled by a wall switch near entry door?

I would remove nearby fixtures and check for loose wires. They are daisy-chained from one to the next so your wiring fault could be at one of the others.
You may even be able to give the wires a little tug and look for movement at the offending fixture.
BTW, the 12V side is not referred to as hot and neutral - just pos. and neg, plus and minus, etc. :)

That's what I would do.