Minimized case:
enum Attribute;
	
@Attribute
class MyTemplate(T) {
}

@Attribute
class MyType {
}

pragma(msg, __traits(getAttributes, MyTemplate)); // prints: tuple()
pragma(msg, __traits(getAttributes, MyTemplate!uint)); // prints: tuple((Attribute))
pragma(msg, __traits(getAttributes, MyType)); // prints: tuple((Attribute))

I think it either result should be the same for non-instantiated type as for instantiated or pragma(msg, __traits(getAttributes, MyTemplate)) should yeld a compile time error.