Issue with provision Startpages Edge to users

We have an issue with adding startpages in Microsoft Edge through a the Device restrictions policy for Windows 10.

We had configured a start page which is properly set for newly enrollled users.

Now we want to change those page and add a second one but the new pages are not getting picked up by Microsoft Edge

I can see the corresponding registry keys in the registry under HKLM:/Software/Microsoft/Policymanager

But the values in Edge are not changed.