EPC and EPC(Column Display) model type differences

Hi,

I've always assumed that EPC and EPC(Column Display) models are simply different structures for the same model type i.e. any symbol or connection on one model type is available on the other in Entire Method.

We've found a situation where this isn't the case - Customer Services accesses Data Cluster.  This connector is available between the symbols on an EPC but not a column EPC. 

Could this be a bug or is there a reason for the difference?