Placeholders are not visible on Android

I have the following code

<VerticalStackLayout Grid.Row="0" Margin="30,10,30,10">
                <Entry Text="{Binding DatoEmpresa.Empresa}" Placeholder="Empresa" Margin="30,5,30,0"/>
                <Entry Text="{Binding DatoEmpresa.PersonaContacto}" Placeholder="Persona de Contacto" Margin="30,5,30,0"/>
                <Entry Text="{Binding DatoEmpresa.Especialidad}" Placeholder="Especialidad" Margin="30,5,30,0"/>
                <Entry Text="{Binding DatoEmpresa.Telefono}" Placeholder="Teléfono" Margin="30,5,30,0" Keyboard="Telephone"/>
                <Entry Text="{Binding DatoEmpresa.Notas}" Placeholder="Observaciones" Margin="30,5,30,0"/>
                <Grid Margin="0,0,0,10"
                    ColumnDefinitions="*,*,*">
                    <ImageButton x:Name="btnSaveUpdate"
                            Grid.Column="0"
                            Margin="20"
                            Command="{Binding SaveDatosCommand}"
                            Source="save_file.png"
                            WidthRequest="20"
                            HeightRequest="20"/>
                    <ImageButton x:Name="btnDelete" 
                            Grid.Column="1"
                            Margin="20"
                            Command="{Binding DeleteDatosCommand}"
                            Source="delete.png"
                            WidthRequest="20"
                            HeightRequest="20"/>
                    <ImageButton x:Name="btnTrabajo" 
                            Grid.Column="2"
                            Margin="20"
                            Clicked="btnTrabajo_Clicked"
                            Source="mantenimiento.png"
                            WidthRequest="20"
                            HeightRequest="20"/>
                </Grid>
            </VerticalStackLayout>

Running the app in MacCatalyst and in IOS the placeholder for the entries are visible, but running the app in Android they are not visible.
Any idea what I need to do to get them to display?
Thanks