ContentView Command binding

Ive run into a problem trying to access command that exist in the code behind, basically this command doesn't fire. OK you might say for button use the Clicked Event, errr!, but there are instances where that is not possible like the TapGestureRecognizer - callbacks are obsolete. Is the only method to generate a separate UserControl VM and bind to that? usually I would self contain the User controls.

<Grid.GestureRecognizers>
            <TapGestureRecognizer Command="{Binding DismissCommand}" BindingContext="{x:Reference thisPopup}"  /> 
         </Grid.GestureRecognizers>
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<!-- The button text is picked up from the code behind DP, the command is a property only -->
<Button Text="{Binding ButtonText}" TextColor="{x:Static theme:PageUI.ButtonTextColour}" Command="{Binding ButtonCommand}" BindingContext="{x:Reference thisPopup}" />
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