In my case, when I first select F4 value help for “Entity Set”, I can see a series of CDS views listed, which are retrieved by the batch request observed in Chrome development tool.
When you now select value help for the third field “Entity Set”, the metadata of this OData service is requested via the url fetched from the previous request. After a successful metadata request, you should see the entity set. If not, usually there is something wrong in the metadata retrieve. You should see detailed error message in Chrome development tool.
