Help: stuck tremolo arm

I’ve got a strange issue with a tremolo arm that won’t come out. I will preface this to say that I have read through a lot of old posts of people experiencing the same, but none of the solutions are helping me.

I own a few EBMM guitars, a couple with push/pull trem arms and I have never had any problem. Recently bought my son a Sterling Luke for his first real guitar. Bought it online and it came without the arm inserted. Can’t say for certain that it’s been out since I first set everything up, but I think that it has. Fast forward to yesterday and he asks if it comes out, and I said sure, just pull on it. Nope. It is stuck like crazy. He insists that he hasn’t done anything crazy to it, and I believe him as he loves the guitar more than anything else he owns and does a good job of taking care of it. I have loosened the small hex screw on the side of the bridge without success. Finally took the whole bridge out and have loosened every screw I have encountered and the arm won’t release. It spins freely, and the screw on the side will lock it down as I’d expect. I even wrapped the arm in a towel to keep it from getting torn up and tried a set of pliers.

Thoughts? I’m far from a guitar setup expert, but have owned many over the years, and can normally fix most issues that I encounter, but I’m lost on this one.

Appreciate anyone who has any insight they can shared.