I have an activity built in Pega 8.5 that uses the Save-DataPage method with Associated Property, and it continued to work in Pega 8.8.   Starting from Pega 23.1, the Activity no longer saves, and it's giving a compile time error. 

"Field configured to be saved is invalid. Reference data has to be configured to be copied to the case."

The set up that I have is that I have a Data Type (L2)  that references a "Query" list of another Data Type (L1) via a List Type Savable Datapage.  The syntax was not failing in Pega 8.8, but it started to fail in Pega 23.1 and above.  I this case, the property is of "Query" type and not of Reference. 

Has anybody experienced this?  Or is this the new behaviour?