Region.Op.REPLACE is deprecated and therefore the exception is thrown:

[AndroidRuntime] java.lang.IllegalArgumentException: Invalid Region.Op - only INTERSECT and DIFFERENCE are allowed
[AndroidRuntime] at android.graphics.Canvas.checkValidClipOp(Canvas.java:779)
[AndroidRuntime] at android.graphics.Canvas.clipRect(Canvas.java:826)
[AndroidRuntime] at com.telerik.widget.calendar.CalendarFragment.drawRows(CalendarFragment.java:589)
[AndroidRuntime] at com.telerik.widget.calendar.CalendarFragment.render(CalendarFragment.java:259)
[AndroidRuntime] at com.telerik.widget.calendar.CalendarScrollManager$FragmentHolder$LayerView.onDraw(CalendarScrollManager.java:136)
[AndroidRuntime] at android.view.View.draw(View.java:20207)

When you have a page with RadCalendar and DayViewSettings properties are data-bound, navigating back in Prism raises a "Cannot destroy page" exception.

The LoadOnDemandItemTemplate's HorizontalOptions setting is ignored on Android, it will always be left aligned.

See this screenshot for comparison of 3 target platforms side-by-side: https://www.screencast.com/t/K5oWBcP0dLQM

The DataTemplate is as follows:
<telerikDataControls:RadListView.LoadOnDemandItemTemplate>
    <DataTemplate>
        <Grid BackgroundColor="Red" 
                   HorizontalOptions="End">
             <Label FontSize="24"
                         HorizontalOptions="End"
                         Text="Load more items"
                         TextColor="Black" />
        </Grid>
    </DataTemplate>
</telerikDataControls:RadListView.LoadOnDemandItemTemplate>

Refer to the attached reproducible.

1. Run app and apply a filter: "Contains 0"

2. Notice #40 is in the correct location, between #30 and #50

3. Press the button on the bottom of the page to go BlankPage and then navigate back.

4. Observe #40 is now at the end of the rows even though the filter is clearly applied.

Look in MainPageViewModel.cs lines 42 to 49. When the navigation back occurs, this code is executed.  I can reproduce the problem with both Replace and Add+Remove operations.

The error message is not showing when the editor is empty and the ValidateAll method is called 

Numeric and date editors are not aligned identically to the other editors inside the dataform