The makro is simple.
It converts the other actor to string. Get the substring. Then is string equal to"markerbp"
I included it so that no other object is placed in the variable. Only the markerbp actors must be success.
The cast failed wire was connected to a print node just printing on the screen that it failed for debug purposes.
The reason for the delay was another issue where the events would fire so rapidly that it would try to cast to the object before the variable knew what was happening. So the cast would fail. After i added a short delay the cast no longer failed.
The at marker variable type is object.
I have no idea why i couldnt cast from the other actor pin like you clearly can do it. Im using 4.6.1
I assumed it should be as simple as you showed in your screenshot.
My original design was exactly the