It's unclear how DataGroup enabled parametric cells that have already been placed in a file are supposed to be updated. For example, I've placed a few of these custom objects in my file but later realize I have to make a change to the parametric cell definition in the cell library. Even if I reselect the updated cell in Catalog Editor, since a local copy of the parametric cell definition already exists how do I update the previously placed instances? Newly placed instances will use the changes I've made in Catalog Editor, but there must be some mechanism for updating those existing instances to match the current library based parametric cell definition.
The simplest way to update existing instances of DataGroup objects that use parametric cells is to use the Modify Properties tool, change any value, and accept:
This process should re-read the parametric cell and update the instance(s) to match any changes made to the cell library definition.