On your side, please consider save your SP List records into a Collection, then use the Collection as data source in your app instead of the Original SP List data source.
Set the OnStart property of the App control to following:
then set the Items property of the Gallery to following:
If the issue still exists, please consider remove the SP list connection from your app, then re-create a new one from your app, then try above solution, check if the issue is solved.
Also please check if there are records existed in your SP List, if not, please add a record into your SP List in your SP List page directly, then refresh the SP List data source in your app, check if the issue is solved.
Please take a try with above alternative solution, then check if the issue is solved. I would also post this issue to my product team, if this issue is solved, I would reply here.
Community Support Team _ Kris Dai If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.