Some Favorites include a GDL object (such as a Favorite Zone that includes a Zone Stamp).
If that GDL object becomes Missing (i.e., its library is not loaded):
•the Favorite is shown in the project and Favorites Chooser with a question mark
•Library Manager lists all missing objects from Favorites
You cannot apply a Favorite that has missing content. However, you can still delete/rename/redefine or edit it, using the Favorites Palette or Tool Settings.
For general information, see Favorites.