dx-with: reverse relation not set when creating db

[stanleyj-edsn]

Given the smallest reproduction scenario I could come up with:

(dx/dx-with
 [{:parent #{[:id "291020"]}
   :id "757796"}])

I expect to see a reverse relation :_parent on the entity [:id "291020"] refering to [:id "757796"] , but I get nil:

{[:id "291020"] {:id "291020"
                 :_parent nil} ; <-- expected: [:id "757796"] 
 [:id "757796"] {:parent #{[:id "291020"]}, :id "757796"}}

is this a bug or is my expectation incorrect? Thanks in advance