We have been able to reproduce the issue and it is currently under investigation.
An error occurred while saving the commentAnonymous commented
It's a simple fix. You need to move your pages down (I'd start with the last page and start as if it's a new layout spread), then pull each panel into that new spread and it fixes the problem. It's just a glitch. Had it happened sporadically. Basically, just re-shuffle the spreads and it will snap back.