If a user makes a macro with a wild card array and then nests it inside of another macro. The wild card array will throw the following error. This can also happens with a StandardMacro like For Each Loop.
Error The type of Target Array is undetermined. Connect something to "Name of Second Macro" to imply a specific type.
Expected: The nested macros would receive array information
Result: Macro throws an error
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-21739 in the post.