Since I upgraded to El Capitan, Spotlight has refused to look up for definitions in my custom dictionary. Instead, it sticks itself with Apple's default English-English dictionary.

Note that the custom dictionary:

 - is already at the top of the dictionary list;
 - still works just fine with Dictionary.app and Quick Lookup (three-finger touch). 

Does anyone know why and have a solution or workaround to this problem? 

Thanks a lot in advance.