If you go to your applications folder and find the InDesign and Illustrator folders, you will see a Fonts folder in each. If you place fonts into these folders, they will be available to that application only. That means that if you put your font in InDesign's Fonts folder, Illustrator won't be able to use it unless a copy is also placed in the Illustrator Fonts folder. You probably had your missing font in the InDesign fonts folder of your previous version. If you still have that version loaded, you will find it there. If you have trashed it, you still have the one in the Illustrator Fonts folder.
You can use the operating system's fonts folders if you prefer, or a font manager, but I believe the application Fonts folders were intended as a quickie way to use a font without having to modify the OS or envoke a font manager, but you can continue to use it for all of your InDesign fonts if you wish. Other than a font not being active in other programs, I don't know of any downside.
I have the same problem. Only the Regular version of some fonts show in the IdCC font chooser, but all other forms are not shown. The font is Skia in this instance (Unique name Skia; 10.0d4e1; 2014-08-18), but it applies to many others. PhotoshopCC also does not display any form but Regular, nor does IllustratorCC.
What's up with this?