Xamarin Designer throws exception - xamarin

Question

I'm working on a current project using Xamarin.Android. I got several view sthat use the same layout. I got used to define everything in a style for this while working with Android Studio. The problem is that Xamarin's Designer doesn't accept that "layout_width" and "layout_height" are defined in a style.
Of course it is a possibility to define those with the views, but it would increase the lines of XML-code quite a bit, and also I'd have to change more than one view if I'd change something.
I already looked into the topic but didn't find a workaround. Maybe someone got a similar problem and might have found a proper solution.
Fragment_Therapist.axml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF"
android:weightSum="7">
<RelativeLayout
android:layout_weight="2"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:src="#android:drawable/ic_menu_gallery"
android:layout_width="250dp"
android:layout_height="250dp"
android:id="#+id/profile_icon"
android:layout_marginTop="30dp"
android:layout_centerHorizontal="true" />
<!-- Profile Name -->
<RelativeLayout
android:id="#+id/sublayout_I"
android:layout_marginTop="25dp"
android:layout_marginLeft="100dp"
android:layout_marginRight="100dp"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_below="#id/profile_icon">
<TextView
android:id="#+id/profile"
android:text="#string/therapistfragment_profile"
android:textColor="#000000"
android:textStyle="bold"
android:minWidth="50dp"
android:textSize="25dp" />
<TextView
android:id="#+id/profile_name"
android:textColor="#000000"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</RelativeLayout>
<!-- Profile Description-->
<RelativeLayout
android:id="#+id/sublayout_II"
android:layout_marginTop="25dp"
android:layout_marginLeft="100dp"
android:layout_marginRight="100dp"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_below="#id/sublayout_I">
<TextView
android:id="#+id/description"
android:textColor="#000000"
android:textStyle="bold"
android:minWidth="50dp"
android:text="#string/therapistfragment_description"
android:textSize="25dp" />
<TextView
android:id="#+id/profile_description"
android:textColor="#000000"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</RelativeLayout>
</RelativeLayout>
<!-- Edit, Info, Delete, Cancel and Save-->
<LinearLayout
android:layout_weight="5"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:weightSum="2">
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="horizontal"
android:layout_weight="1"
android:weightSum="2">
<RelativeLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1">
<Button
android:id="#+id/edit"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_marginBottom="15dp"
android:layout_marginLeft="25dp"
android:layout_marginRight="25dp"
android:layout_marginTop="15dp" />
</RelativeLayout>
<RelativeLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1">
<Button
android:id="#+id/info"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_marginBottom="15dp"
android:layout_marginLeft="25dp"
android:layout_marginRight="25dp"
android:layout_marginTop="15dp" />
</RelativeLayout>
</LinearLayout>
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1"
android:weightSum="4">
<LinearLayout
android:id="#+id/left"
style="#style/PlaceHolder" />
<RelativeLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="2">
<Button
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_marginBottom="15dp"
android:layout_marginLeft="25dp"
android:layout_marginRight="25dp"
android:layout_marginTop="15dp" />
</RelativeLayout>
<LinearLayout
android:id="#+id/right"
style="#style/PlaceHolder" />
</LinearLayout>
</LinearLayout>
</LinearLayout>
styles.xml
<?xml version="1.0" encoding="utf-8" ?>
<resources>
<style name="PlaceHolder">
<item name="android:layout_height">match_parent</item>
<item name="android:layout_width">match_parent</item>
<item name="android:layout_weight">1</item>
</style>
</resources>