Playback stops like a dropout but it's not

I tell ya, for the life of me....
 
In this project, playback always stops in the exact same place in the middle of the song. I just tap Space and it continues right along every time. There's no red DROPOUT warning at the bottom, and it's not at a place where a lot more instruments come in or processes or anything else that might lead me to believe it's a typical dropout. I've tried including the stop place in a loop, and even in the loop it stops there. No matter what, the song always stops at this same spot with no obvious indication as to why. This project isn't very big either. Five vocal tracks, typical rock band tracks, some processing but nothing crazy. It's been intermittent over the past few days, but now is consistently doing it. Before when it was intermittent I don't remember if it was in this same place or not.
 
I experience this behavior fairly often on any given project. Seems to have only started with X3.