I am having the same problem with AGO mapping applications. When I build the web map, pop up sensitivity is fine. When the data is shared through one of the story map templates you have to be very precise on the spot you click in order to have anything to happen. Can the sensitivity be adjusted?
If you are using identify you can set up a "tolerance" for your IdentifyParameters.
https://developers.arcgis.com/javascript/jsapi/identifyparameters-amd.html
Thanks,
Luci
How do you set that property for a Map Service published to ArcGIS for Server and consumed in ArcGIS Online?
I don't think you can. ArcGIS Online maps use a default for all query tasks. It looks like the app creates a buffer (actually an envelope) around the click point . I doubt it can be updated.
I had the same issue when publishing a point feature class rendered at 12 point within the ArcGIS Pro session (45 pixel size in web map) and published to Portal. The 'pop-up click sensitivity radius' or 'hit box' performed fine in the mapping session but when published the user had to click the center of the point in order for the pop-up to open otherwise was met with a no data message.
The fix (solved by one of my brilliant colleagues) was to work with the 'feature layer service' rather than the map service layer ('https://mapserviceURL' vs 'https://mapserviceURL/0'). The reason for this appears to be that the map service is rendered on the server side, while the feature service is rendered on the client-side. Map image services serve up images of the data, however feature layer services serve the underlying data itself and allows for editing which entails client-side rendering.
HTH,
Yuri