Server 2012r2 RDS - Start Screen

I'm in the process of setting up an RDS server. It will be multi-tenant, so it's locked right down. All user profile data is stored on the file server using GPO folder redirection.

I want to lock the start screen right down to only show what they have access to: Office, our application, "This PC", Desktop, Notepad and Calculator.

I have logged as an admin user and configured a start screen to suit. Used Export-StartLayout to get my layout XML. I have set the use start layout GPO to the user share where it is located.

The issue is:

I can't get all the apps to show on the start screen. Office shows fine, but our app won't show along with notepad and "this PC".
A little stuck on this one...

Layout.XML

<launcher version="2">
  <view name="Start">
    <group name="Desktop">
      <tile AppID="{C9BAE21F-221E-405F-BA9D-FAC741829F4F}\Office Companion.lnk" size="square150x150" FencePost="0" />
      <tile AppID="Chrome" size="square150x150" FencePost="0" />
      <tile AppID="{1AC14E77-02E7-4E5D-B744-2EB1AE5198B7}\notepad.exe" size="square150x150" FencePost="0" />
      <tile AppID="Microsoft.Windows.Computer" size="square150x150" FencePost="0" />
      <tile AppID="Microsoft.Windows.Desktop" size="square150x150" FencePost="0" />
    </group>
    <group name="Microsoft Office">
      <tile AppID="{7C5A40EF-A0FB-4BFC-874A-C0F2E0B9FA8E}\Microsoft Office\Office15\ONENOTE.EXE" size="square150x150"  FencePost="0" />
      <tile AppID="Microsoft.Office.OUTLOOK.EXE.15" size="square150x150" FencePost="0" />
      <tile AppID="{7C5A40EF-A0FB-4BFC-874A-C0F2E0B9FA8E}\Microsoft Office\Office15\WINWORD.EXE" size="square150x150"
      FencePost="0" />
      <tile AppID="{7C5A40EF-A0FB-4BFC-874A-C0F2E0B9FA8E}\Microsoft Office\Office15\EXCEL.EXE" size="square150x150"
      FencePost="0" />
    </group>
  </view>
</launcher>

This references Windows 8/8.1, but applies to 2012/R2. Be sure to read to the bottom as there are some great QAs for things like you're experiencing where not everything shows up. I've included a screenshot for reference, but basically when users don't see all the tiles/apps it's USUALLY because of three major things:

A) You didn't apply the layout to the default profile

B) You didn't install/configure a custom app, or third party app, correctly on the computer in question, and the computer doesn't recognize it as being installed locally.

C) Permissions used to export/import the XML/start layout.