I have the same thing. Sometimes when I'm sleeping if my neck is bent funny it pops out of place or if I cough really hard when I'm sick. But when they do imaging everything looks normal because it's not popped out at the time of imaging. I used to get it in place super easy and now it's getting harder and happens more often. Going on 8-10 years of this. It feels like I'm popping cartilage back into place that pops out. Also make swallowing unbearably painful