It seems that Is Valid function/macro does not take a ref of struct as an input.
Engine version: 4.15.1
1.Create a local variable with type of array of struct. (any type.)
2.Get a reference of element with Get node. (I think it returns a ref after 4.12.)
3.Try to connect it to Is Valid function or macro node.
Message “XYZ structure is not compatible with object reference.” is shown.