Update: I went into the "corrupted" combined file and started accepting formatting changes (since I don't specifically need those redlines as much as I need the content change redlines), and after I accepted a couple hundred changes the document began to behave better. I was able to change it back to Print view, and everything else seems to be working correctly again. So now I think it wasn't actually corrupted, just overburdened with tracked changes.

So it looks like the problem is solved.