Sorry for the delay caused.
We have checked the reported query from our side. We would like to know that when any item is loaded inside Tabview without any defined height, loaded item’s view will be hidden inside the tabview if item size exceeds tabview height. This same issue will occur in xamarin listview also. You can resolve this issue by defining specific Height to the Rowdefinition of Grid which is loaded inside TabView in your sample like below.
<syncfusion:SfTabItem Title="Contact" >
We have attached the sample for your reference and you can download the same from the following location.
Please let us know if you require any further assistance.