Just a technical question, not a problem. I’m using the font Berthold Akzidenz Grotesk (PostScript version) that comes with a variety of faces, from Light to Extra Bold, some of them with their italics. The shortcut cmd+shift+i works for Regular and Bold but has no effect on Light and Medium, which have their italic counterparts. I don’t expect the shortcut to work with Extra Bold and Super, which don’t have an italic version, but can someone explain why it behaves like this? Does it have anything to do with the old setup of four faces, usually Roman, Italic, Bold, and Bond Italic? Would it still behave like this as an OpenType? Or does it simply depend on how the set was assembled in the first place?
This kind of mapping has been a problem in complex font families for many years. It’s similar to the problem that some people have with fonts that don’t have a font labeled “Italic” but instead “Oblique” and the shortcut doesn’t work. It has to do with InDesign getting confused about what maps to what.
I believe in the old PostScript fonts, this was a particular problem because it had to be mapped properly in the font, and sometimes those mappings got confused. I remember about 20 years ago there was some tool called Font Family Harmonizer or something like that, which would let you reset what shortcut would map to what.