I found a file in which many curves were missing. I stripped it down as small as possible and it appears the curves are actually there somewhere but not visible.
In the attached file, no curves show up. But if I do <CMD/A> the properties panel tells me I have three curves selected. Yet I cannot zoom to the selected curves.
The file is also 25MB once it has been purged. (Hint: Try import).
Problem Curves.zip (12.3 MB)