The use of fonts in applications where they are more than just text requires a higher quality than text uses, and lower quality/possibly troublesome fonts (or font styles) may just be ignored.
Illy is particularly particular.
Apple OpenType is somewhat particular. Not all of it can be accessed by all applications. This is also the case for some of the Ligatures or alternatives in Apple's fonts. They can be accessed in TextEdit, but not Illustrator.