Grid not fetching values through API call

Hi ,

I have a grid which fetches values through API call on clicking a button. I'm able to fetch the values when I click on that button in interface but not in Site.

This interface is being called as an action in Process model and I have configured all the rule inputs in the Process model.

Here in interface when I click on the Search Multi Agreement Activities I'm able to get values in below grid.

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And in Site when I click on the button, its just showing the empty grid

Can someone help me what could be the issue or what I missed here.