First off might I offer you a suggestion...if you added some link nodes your flow wouldn't look so confusing.
Not having the actual flow, the pitcure seems to indicate there are threemsg's able to get to the join.
You say the
the values in the object ["f52b72ff.9cc7"] are not available. I see no reference to that object is what you have provided.
My second suggestion is you add a
debug node to the output of each of the nodes connected to the join. Once you have captured the data, you could create a small flow where you have three
inject nodes setting up msgs with the data you captured in the
debug nodes and feed that into a copy of the
join node and connect that to a
That way you could provide a small flow that reproduces your issue and make it easier for someone to help you.