This is an indication of an open neutral somewhere on this circuit.
Could be in the panel, could be in one of the boxes.

 

Are there other outlets on this circuit that test correctly? In addition to Speedy’s suggestion, could be in the last device box that is testing correctly. Also try tracing the circuit and look for junction boxes in the attic or basement that might have incorrect splices.

 

It's a double-wide, I posted on here earlier this week about an open service neutral. Come to find out, thats what the previous issue was. Tree branch popped the service neutral off at the transformer. That's fixed. Now there are 5 receptacles in this room. All tie in at the ceiling fixture. Don't ask. The light and switch work. The receptacle running the hot, comes back correct, 3 of 5 come back HOT/GROUND Reverse and 1 of 5 come back Open Neutral.???

 

The one showing open neutral has no load on it.

The ones showing hot/ground reversed have a load applied on it, making the neutral appear "hot" and the subsequent false reading. You'll notice that your plug tester's instructions will tell you that it won't be able to discern more than one hot wire in the outlet.

With the neutral being "hot" due to the backfeeding from the applied loads, it fools the tester.

Probably a loose connection in that ceiling box.