Oh… If you see the description of Async nodes, you will see that the they marked (Async) already create their own instance.
This was requested by a few users… So you actually do not pass in an instance to Async nodes. You just pick an asset from it’s drop-down list.
Anything not Async needs a slot instance.
To clean up what you did there, you will probably have to restart the editor, since delegates got stuck.