Drag & drop assets within the Assets tab on the any of the Commerce Entities (Categories, Products, Variants, etc) does not work.
CommerceMediaCollectionEditorDescriptor uses the LinkableTypes property from MediaRepositoryDescriptor to set the AllowedTypes in the editor descriptor, but the LinkableTypes is never set.
Nice to have besides fixing the bug:
AllowedTypes (from CommerceMediaCollectionEditorDescriptor) should allow not only Optimizely Media Content Types, but also content coming from 3rd party (e.g. DAM connectors)
Are you reporting a bug or help on fixing an issue?
If you are looking for a workaround, you can create your own implementation (which extends CollectionEditorDescriptor<CommerceMediaModel> ), and use this attribute
[EditorDescriptorRegistration(TargetType = typeof(ItemCollection<CommerceMedia>), UIHint = SystemUiHint.CommerceMediaCollection, EditorDescriptorBehavior = PlacedLast )]
Then you can add your types into AllowedTypes
I think that should work, but I haven't tried myself