This requires access to the Designer Studio to create an Association rule that defines how you want to join the case type and data type for reporting. Currently, we do not create the association automatically. The reason we decided not to do this is that data types are often used to access information via an integration to another system. You often start by defining a data type and using local records to get started so that you don't need to wait for the integration to be built. Later, the integration can be added as the source of the data without impacting your case type.

If you plan to keep all of the data type records local in Pega, you can create an Association for reporting. Association rules are under the SysAdmin category. You will likely want define it to include matching rows (i.e. an inner join) on the data refererence field pyGUID against the pyGUID in the data type table.

Include matching rows against your data type class where the .pyGUID of the data type equals .DataRefField.pyGUID

Here is more information about associations:

https://pdn.pega.com/when-and-how-create-association-rule-support-reporting

https://pdn.pega.com/sites/pdn.pega.com/files/help_v72/procomhelpmain.htm#zstandardrules/rule-obj-association.htm