Why don't underscores appear in text?

[DBlomgren]

Hello all,



By underscores, I mean the character you type when you press Shift and the key next to zero on the keyboard, you know, the shift part of the hyphen key. In the attached picture, there are two places underscores don't show up, and I've circled them in red. Yet there's one place where they do show up. I've tried copying the "good" underscores to where the "bad" underscores are and they turn invisible.

I've tried removing formatting from the invisible underscores (select, Ctrl-Space) with no resulting change.

Any guesses?