What are the reasons that sometimes resolvers are called with nil as param despite there being a key specified that is actually there?

I am using pathom standalone within a re-frame app, I am reading though fulcro doc because I'd like to improve the way I do data normalization. Currently I parse the server response with defmethods to normalize it into app-db. I am under the impression that fulcro is doing normalization under the hood, does it manage to get normalized response from the pathom server? Is it possible to get that without fulcro? Not getting a deeply nested tree from the pathom parser but a flatter structure instead? for instant in a big query that ask for a list of user items, get the users details at the same level as the items details, so that when multiple items belong to a single user, the user and his details are only present once in the response, while the item only contains the user id