Asset libraries should be directories on disk. By manually entering a file path it was possible to have a single blend file as asset library, but that was not a designed-for situation, and it doesn't play well with the asset catalog system.
Asset libraries should be directories on disk. By manually entering a file path it was possible to have a single blend file as asset library, but that was not a designed-for situation, and it doesn't play well with the asset catalog system.