In the supplied example, the vertical alignment of envGrid1/envGrid2 is incorrect, both should align to the top edge.
If you comment line 19 in MainPage.xaml.cs, it works ok.
If you comment line 19 and uncomment line 21 in MainPage.xaml.cs, it works ok.
It seems like the Height = auto causes the problems, however in the real application the row has a dynamic height and I can't work give the row a fixed height (second row should fill screen) and I don't want to calculate the height.