Hi @Tim Warfe? , amazing solution, congrats! I like it a lot.
I think it isn't a bug I think that the search radius changes when the map zoom changes. I mean that at Level 10 SSA finds many records within the radius, at Level 19 SSA finds just a record around the Address you chosen. I would suggest to set a different value of "Callout Search Width (px)" for this layer in the SSA Admin Console > Map Configs > Maps. Let me know how is going... in negative case I will have a chat with the SSA Engineers.