My first suggestion is "ensure" it is completely latched in the "fold up" position, I've had it happen a few times where the "up" latch isn't completely seated and the "swing out" handle feels as if it's broken. Worse case is the mechanism internally or it's plastic clips have failed internally in the tailgate.
There are several posts and unfortunately the 2G Ridgeline suffers from some of the same issues. Try using the "search" in the upper right corner and if I find any helpful links I'll add them.
I tore my tailgate apart the first time it happened to me thinking it was a broken rod or tab. it was all good in there.
All it needed was to be closed all the way. There is a small bumper on the lower corner of the frame when the tailgate gets shut. It it isn't closed enough the handle won't operate. Give it a little shove in the bottom corner and see if that fixes it.
I have had the tailgate controls repaired or replaced 4 times. After some use it sticks and will not operate. We need to get some class action work done here. Evidently Honda has known about this issue for some time now.