DataGrid is added inside pages that can be accessed through shell flyout menu. 

And the exact steps to reproduce the issue:

Go to page GridOne page in flyout menu.
Enter any element by double tap. this navigates to another page - SubGridPage 
On SubGridPage again double tap any element. this navigates to another page - InnerModel 
When you are in InnerModel page select from flyout menu GridTwo page
On GridTwoPage double tap any element, this navigates to another page - SubGridPage 
On SubGridPage double tap any element. this navigates to another page - InnerModel 
When you land on InnerModel page go back to Grid One on flyout menu.
When you are in the GridOne InnerModel, press the back arrow. 
It navigates to the SubGridPage. but the DataGrid is not visualized.