Replace the Nanoflow Datasource on the Inner DDG with a Microflow Datasource: Nanoflow data sources on the inner DDG are running client-side and won't automatically react to server-side commits. If you switch the DDG's data source to a microflow, then a "Refresh in Client" on the ProgramLocationResource entity in your onChange microflow will force it to re-execute.
Steps:
ProgramLocationResource objects with Refresh in Client = YesA microflow data source will be re-run whenever the data widget is refreshed — and refreshing is triggered when the objects it depends on are committed with Refresh in Client = Yes.