Text Disappearing? Illustrator

[camronr]

I have a font and all of a sudden the medium and regular styles have gone invisible. I can change font or go to light and it will reappear. If I hover over that style it will go invisible again. It will reappear or go invisible again at different levels of zoom. 

Anyone else run into this?

[Monika Gause]

Which version? Which system?

Do you use font management?

Does the font work in other applications?

Has the font been checked and is OK?

Which font is it?

Is the correct language applied to the characters?