You can see it here in Accordance's screenshot of the new Devotions on the GNT--do Greek characters not show up properly in sidebar table of contents? (Second from the bottom has a dash with nothing before it, but in the book it is preceded by a Greek word.)
I had a similar issue in a User Tool I was creating--I can't remember now what character it was (if it was Greek or punctuation): it showed up fine in the tool itself, but not in the sidebar navigation area. Or maybe it's an issue of what kind of font is used?
If I can find the issue again in the User Tool I was trying to make, I'll post again.