Xamarin.Forms.Xaml.XamlParseException: MarkupExtension not found for trans:Translate using a PCL in Release Mode

I'm pretty desperate finding the solution for the problem stated below.

I have a cross platform solution which has 4 projects,

3 OS specifics 
    MyApp.android,
    MyApp.Winphone,
    MyApp.IOS
and a PCL project
    MyApp.BLL

inside the MyApp.BLLbll, I'm using the MyApp namespace and in the root I have the class TranslateExtension.cs

namespace MyApp
{
    [ContentProperty("Text")]
    public class TranslateExtension: IMarkupExtension

{
    readonly CultureInfo ci;
    const string ResourceId = "MyApp.Resources.AppResource";

    public TranslateExtension()
    {
        ci = DependencyService.Get<ILocalize>().GetCurrentCultureInfo();
    }

    public string Text { get; set; }

    public object ProvideValue(IServiceProvider serviceProvider)
    {
        if (Text == null)
            return "";

        ResourceManager resmgr = new ResourceManager(ResourceId
                            , typeof(TranslateExtension).GetTypeInfo().Assembly);

        var translation = resmgr.GetString(Text, ci);
        try
        {
        if (translation == null)
            {
#if DEBUG
                throw new ArgumentException(
                    String.Format("Key '{0}' was not found in resources '{1}' for culture '{2}'.", Text, ResourceId, ci.Name),
                    "Text");
#else
                translation = Text; // HACK: returns the key, which GETS DISPLAYED TO THE USER
#endif
            }
        }
        catch (Exception exp) {
        }
        return translation;
    }
}

inside the Xamarin Forms I'm using the following to enable the translation for the labels, etc.

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MyApp.Views.RegisterWebServiceXaml"
             xmlns:trans="clr-namespace:MyApp;assembly=MyApp.BLL"
             IsBusy="{Binding IsWorking}"
             >

  <ContentPage.Content>
    <StackLayout Orientation="Vertical" VerticalOptions="FillAndExpand" Padding="0,75,0,0">
          <Entry Text="{Binding Path=OrganizationId, Mode=TwoWay}" Placeholder="{trans:Translate OrganizationId}" Style="{StaticResource LoginStyle}" />
          ...
          <Label Text="{trans:TranslateUpper Next}" x:Name="LoginLabel" HorizontalOptions="Center" Style="{StaticResource BasicLabel}" />
    </StackLayout>
  </ContentPage.Content>
</ContentPage>

This is working like a charm using the debug modus, but when I try to compile the solution for Android in release mode, my application is suddenly stopping directly after loading the splashscreen stating 'MyApp is stopped'

looking in the Application output, I can find the following error message:

[Xamarin.Insights] Warning: Unhandled exception: Xamarin.Forms.Xaml.XamlParseException: MarkupExtension not found for trans:Translate
[Xamarin.Insights] at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () <0x00028>
[Xamarin.Insights] at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>m__0 (object) <0x0003f>
[Xamarin.Insights] at Android.App.SyncContext/<Post>c__AnonStorey0.<>m__0 () <0x00027>
[Xamarin.Insights] at Java.Lang.Thread/RunnableImplementor.Run () <0x0003f>
[Xamarin.Insights] at Java.Lang.IRunnableInvoker.n_Run (intptr,intptr) <0x0003b>
[Xamarin.Insights] at (wrapper dynamic-method) object.44dc0140-8f03-4bf1-a261-186aa2a7ef42 (intptr,intptr) <0x0003b>
[art] JNI RegisterNativeMethods: attempt to register 0 native methods for md52ce486a14f4bcd95899665e9d932190b.JavaProxyThrowable
[AndroidRuntime] Shutting down VM
[AndroidRuntime] FATAL EXCEPTION: main
[AndroidRuntime] Process: MyApp.MyApp, PID: 32091
[AndroidRuntime] java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
[AndroidRuntime]    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1184)
[AndroidRuntime] Caused by: java.lang.reflect.InvocationTargetException
[AndroidRuntime]    at java.lang.reflect.Method.invoke(Native Method)
[AndroidRuntime]    at java.lang.reflect.Method.invoke(Method.java:372)
[AndroidRuntime]    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1389)
[AndroidRuntime]    ... 1 more
[AndroidRuntime] Caused by: md52ce486a14f4bcd95899665e9d932190b.JavaProxyThrowable: Xamarin.Forms.Xaml.XamlParseException: MarkupExtension not found for trans:Translate
[AndroidRuntime] at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () <0x00028>
[AndroidRuntime] at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>m__0 (object) <0x0003f>
[AndroidRuntime] at Android.App.SyncContext/<Post>c__AnonStorey0.<>m__0 () <0x00027>
[AndroidRuntime] at Java.Lang.Thread/RunnableImplementor.Run () <0x0003f>
[AndroidRuntime] at Java.Lang.IRunnableInvoker.n_Run (intptr,intptr) <0x0003b>
[AndroidRuntime] at (wrapper dynamic-method) object.44dc0140-8f03-4bf1-a261-186aa2a7ef42 (intptr,intptr)<0x0003b>[AndroidRuntime][AndroidRuntime]    at mono.java.lang.RunnableImplementor.n_run(NativeMethod)[AndroidRuntime]    at mono.java.lang.RunnableImplementor.run(RunnableImplementor.java:29)[AndroidRuntime]    at android.os.Handler.handleCallback(Handler.java:739)[AndroidRuntime]    at android.os.Handler.dispatchMessage(Handler.java:95)[AndroidRuntime]    at android.os.Looper.loop(Looper.java:145)[AndroidRuntime]    at android.app.ActivityThread.main(ActivityThread.java:5944)[AndroidRuntime]...4 more

Does any body has a solution for this problem? I can't find it. I have tried using the several namespaces ( MyApp.android, MyApp, MyApp.BLL, MyApp.MyApp ), but until now I haven't found the right one.

Why is this working in Debug mode and not in Release/App store mode?

Check the project settings, make sure linking is turned off or SDK-ony

 .

If it was "Link all assemblies" and without it your code becomes too big you may want to instead use the [Preserve] attribute on your class.

See this page for more info on Xamarin Linker