This is an old issue, but I thought I'd share it regardless. I had this same issue and found that while it worked fine in FlutterFlow test mode, but when testing on a mobile iOS devices the List View would appear grey and not load.

In the end, it turned out the mobile iOS app wasn't accepting the JSON structure I was using.

The below JSON worked fine in FlutterFlow test mode when accessing the '$.notification[0].NotificationMessage' JSON Path value.

{\"activityId\": 159260,

\"activityTitle\": \"Estimates Approved\",

\"createdDate\": \"2024-04-24T10:00:57\",

\"notification\": [

{

\"notificationId\": 27665,

\"NotificationMessage\": \"The status for Estimate 'E-00647 - 0906 V1' has been updated as 'Awaiting Approval' by Martin.\",

\"ReadNotification\": \"0\",

\"HiddenNotification\": \"0\"

}

]

}

The List View started working in mobile IOS as soon as I simplified my JSON structure to a single Object.

{

\"notificationId\": 27665,

\"activityTitle\": \"Estimates Approved\",

\"createdDate\": \"2024-04-24T10:00:57\",

\"createdBy\": \"Martin\",

\"notificationMessage\": \"The status for Estimates 'Estimate 'E-00647 - 0906 V1' has been updated as 'Awaiting Approval' by Martin.\"

}

I hope this helps anyone who might be experiencing the same issue/cause.

Grey Screen issue, will pay to fix today