Unknown warning in Model Advisor

Hi,

I receive the following error when running the Code Inspector compatibility checks in Model Advisor:

One or more output signals of the following blocks do not have their custom storage class Type set to 'Unstructured', or do not have their Data initialization set to 'None', or specify a signal object with a non-empty InitialValue.

I have not seen a storage class that is "Unstructured". I am specifying the data types of the operations in the block it flags, and when I run Code Inspector, it cannot process these blocks.

What does this mean?