@Harpreet Sangar Spent a few hours on it this morning, really would appreciate some further help - I recreated the collection and the base query worked so maybe I did alter it at some point. However, the new error I can't get past is "Failed to join on

posts

collection: Error with filter field `topic_id`: Numerical field has an invalid comparator." This returns values:

{
      q: "*",
      collection: "topics",
      filter_by: "$posts(topic_id:=4)",
      include_fields: "$posts(*)",
    }

This does NOT work - nor any variation of this that I've tried: *I just get "*Failed to join on

posts

collection: Error with filter field `topic_id`: Numerical field has an invalid comparator."

{
      q: "*",
      collection: "topics",
      filter_by: "$posts(topic_id:=topic_id)",
      include_fields: "$posts(*)",
    }