400 bad request error with event segmentation

This event with event property and value is valid as seen from the chart above. But my API call keeps returning a 400 bad request error:

https://amplitude.com/api/2/events/segmentation?e={"event_type":"A_DomainEnter"}&start=20240214&end=20240216&s=[{"prop":"gp:StoreCode","op":"is","values":["COOP"]}]

I’ve tried with both Postman and Javascript, and the response is good if I just remove the “s” parameter, so it’s definitely not an issue with authorization or anything.

I’ve also tried it like this, 400 bad request as well:

https://amplitude.com/api/2/events/segmentation?e={"event_type":"A_DomainEnter","filters": [{"subprop_type": "event", "subprop_key": "gp:StoreCode", "subprop_op": "is", "subprop_value": ["COOP"]}]}&start=20240214&end=20240216

Any help appreciated, thanks in advance.