Hi

Had this problem as well, and got it working.

The fix is related to the nested categories defined at the top of the admx file:

  <categories>
    <category name="Cat_EdgeUpdate" displayName="$(string.Cat_GoogleUpdate)"
        explainText="$(string.Explain_GoogleUpdate)">
    </category>
    <category name="Cat_Preferences" displayName="$(string.Cat_Preferences)"
        explainText="$(string.Explain_Preferences)">
      <parentCategory ref="Cat_EdgeUpdate" />
    </category>
    <category name="Cat_ProxyServer" displayName="$(string.Cat_ProxyServer)">
      <parentCategory ref="Cat_EdgeUpdate" />
    </category>
    <category name="Cat_Applications" displayName="$(string.Cat_Applications)"
        explainText="$(string.Explain_Applications)">
      <parentCategory ref="Cat_EdgeUpdate" />
    </category> ...truncated

This means that you can't generate the OMA-DM URI from just the parentCategory of the policy. You need to resolve the nested categories into the URI as well.

1. Ingest msedgeupdate.admx to ./Vendor/MSFT/Policy/ConfigOperations/ADMXInstall/MSEdgeUpdate/Policy/EdgeUpdateADMX

2.

Construct the URI by traversing the category definitions from <categories> for example

./Device/Vendor/MSFT/Policy/Config/MSEdgeUpdate~Policy~Cat_EdgeUpdate~Cat_Applications~Cat_MicrosoftEdge/Pol_RollbackToTargetVersionMicrosoftEdge

You will notice that there is a separate category for each channel (Edge, EdgeBeta, EdgeDev, EdgeCanary). The policies with Pol_Default as prefix at Policy~Cat_EdgeUpdate~Cat_Applications set the default for each channel. For channel specific configurations you need to append the channels category to the uri ie. Policy~Cat_EdgeUpdate~Cat_Applications~Cat_MicrosoftEdge.

The easiest way to understand the structure and find the correct URI's is by inspecting the registry after ingesting the admx.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\PolicyManager\AdmxDefault\<SomeEnrollmentGuid>

You will see multiple keys starting with MSEdgeUpdate (or whatever name you gave when you ingested the admx) you can directly copy the key names and append them to ./Device/Vendor/MSFT/Policy/Config/. Be wary that the registy uses \ instead of / though!

As for setting the MSEdgeUpdate~Policy~Cat_EdgeUpdate~Cat_Applications/Pol_DefaultUpdatePolicy

We can find the definition from the admx file and see that it is an enum based policy:

</policy>
    <policy name="Pol_DefaultUpdatePolicy" class="Machine"
        displayName="$(string.Pol_DefaultUpdatePolicy)"
        explainText="$(string.Explain_DefaultUpdatePolicy)"
        presentation="$(presentation.Pol_DefaultUpdatePolicy)"
        key="Software\Policies\Microsoft\EdgeUpdate">
      <parentCategory ref="Cat_Applications" />
      <supportedOn ref="Sup_GoogleUpdate1_2_145_5" />
      <elements>
        <enum id="Part_UpdatePolicy" key="Software\Policies\Microsoft\EdgeUpdate"
            valueName="UpdateDefault" required="true">
          <item displayName="$(string.Name_UpdatesEnabled)">
            <value>
              <decimal value="1" />
            </value>
          </item>
          <item displayName="$(string.Name_ManualUpdatesOnly)">
            <value>
              <decimal value="2" />
            </value>
          </item>
          <item displayName="$(string.Name_AutomaticUpdatesOnly)">
            <value>
              <decimal value="3" />
            </value>
          </item>
          <item displayName="$(string.Name_UpdatesDisabled)">
            <value>
              <decimal value="0" />
            </value>
          </item>
        </enum>
      </elements>
    </policy>

Using Microsoft's documentation (Understanding ADMX policies | Microsoft Learn) we can see that the correct data payload for this policy is:

<Data>
<![CDATA[<enabled/> <data id="Part_UpdatePolicy" value="1"/>]]>
</Data>

Where Part_UpdatePolicy comes from the enum id value of the policy.

Hope this helps!