Customize start menu from Windows through GPO not working

I am trying to implement through a GPO, a new Start Menu Layout but no matter what I do it simply dont apply.

This is the XML of this Layout:

<?xml version="1.0" encoding="utf-8"?>
<LayoutModificationTemplate
    xmlns="http://schemas.microsoft.com/Start/2014/LayoutModification"
    xmlns:defaultlayout="http://schemas.microsoft.com/Start/2014/FullDefaultLayout"
    xmlns:start="http://schemas.microsoft.com/Start/2014/StartLayout"
    xmlns:taskbar="http://schemas.microsoft.com/Start/2014/TaskbarLayout"
    Version="1">
  <LayoutOptions StartTileGroupCellWidth="6" StartTileGroupsColumnCount="1" />
  <DefaultLayoutOverride LayoutCustomizationRestrictionType="OnlySpecifiedGroups">
    <StartLayoutCollection>
      <defaultlayout:StartLayout GroupCellWidth="6" />
    </StartLayoutCollection>
  </DefaultLayoutOverride>l

And I have it here:

From GPO (server side) perspective I've setup this (even from a local directory):

From GPO (client side):

And linked to a group were I've a user to test this GPO, but still no changes from it when I login with that user on a fully updated Windows 10 Pro.

I've already reboot this machine several times.

Anyone knows what am I missing here?

It looks like you want to remove all the tiles shown in the Start Menu, however, your XML file specifies a Partial Layout (=a group of tiles Windows will add to the existing ones): [...]LayoutCustomizationRestrictionType="OnlySpecifiedGroups"[...]

You should deploy a full Start Layout if you want to change existing tiles. I'd recommend reading the documentation here: https://docs.microsoft.com/en-us/windows/configuration/customize-and-export-start-layout and customize the start layout on your test computer, then export it with Export-StartLayout as shown in the documentation.