So I was out in the garage working out, and between sets, I pulled the FNX-45 out of the safe.  I grabbed an empty mag to go through a slow motion reload.  Slide locked back, empty mag in, I pushed the mag release, and the mag popped out about 1/2", then hung up.  I tested it with several mags, and they all hung up.  We've had some cold weather here recently, so I'm wondering if it's related.  It was always above freezing in the garage though.

All mags have always dropped free.  Inside of the frame is clean and dry, no lube at all on the receiver or mags.  I can insert about 1.5" of the mag into the frame and feel the friction between the mag and the frame.  In fact, the mag will hang in the pistol if I just push it in slightly.

Anyone else have an issue with it?  Pistol and a mag are inside warming up right now.

So I solved this problem.  And I don't know how well it bodes for the FNX.

I used to squeeze on the bottom sides of the magwell to see if I had one of the squishy frames.  I'd also do it to show people that I didn't.  I do have remarkably strong hands.  I was messing around with the slide off, looking at how the mag contacted the sides of the frame.  I inserted a mag about 2", then levered it side to side just a bit.

Mags drop free now.  

Apparently I stretched it out again (there's a joke in there somewhere).  I suppose I should see if this experiment is repeatable or not, but I don't know if I want to.  LOL.

I had the same problem with mine.
So I sent it back to FN for repair.
They kept it a month and all they did was put some stinky oil on it and sent it back.
So in other words it still had the same problem.

I had sticky mags too, sent it back and they actually filed/shaved the inside of the magwell towards the back top of the gun. Mags drop free now