You are looking for the contrained by function as explained here: https://docs.mendix.com/refguide7/reference-selector
Unfortunately this explanation never reached the Mx9 documentation. But it still works as described here.
Regards,
Ronald
You can try to add in Input Reference Set Selector a constraint path in 'Selectable objects' tab.
I have called a microflow in selectable objects. Microflow is returning correct list of centers for the selected location. However on the page center list is coming empty. Below is my microflow. Also in logs I am printing the center names that are coming as expected. What is missing?