A custom mobile Outlook add-in is not loading, which is working well in the Outlook Web version and client

Question

We have created a manifest file by following the link as mentioned in the Microsoft Documentation

https://learn.microsoft.com/en-us/office/dev/add-ins/outlook/mobile-event-based?tabs=jsonmanifest

and uploaded as follows:

<?xml version="1.0" encoding="UTF-8"?>
<!--Created:ce44715c-8c4e-446b-879c-ea9ebe0f09c8-->
<!-- To learn about the Office Add-ins XML manifest, see https://go.microsoft.com/fwlink/?linkid=2252563. -->
<OfficeApp 
          xmlns="http://schemas.microsoft.com/office/appforoffice/1.1" 
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
          xmlns:bt="http://schemas.microsoft.com/office/officeappbasictypes/1.0" 
          xmlns:mailappor="http://schemas.microsoft.com/office/mailappversionoverrides/1.0" 
          xsi:type="MailApp">


  <!-- IMPORTANT! Id must be unique for your add-in, if you reuse this manifest ensure that you change this id to a new GUID. -->
  <Id>d9ff0360-b988-4fd1-a79e-755e97ba774e</Id>

  <Version>1.0.0.0</Version>
  <ProviderName>Outlook Mobile Test</ProviderName>
  <DefaultLocale>en-US</DefaultLocale>
  <!-- The display name of your add-in. Used on the store and various places of the Office UI such as the add-ins dialog. -->
  <DisplayName DefaultValue="OutlookMobileTest" />
  <Description DefaultValue="OutlookMobileTest"/>

  <IconUrl DefaultValue="https://autodisc.vertexcs.com:86/Images/icon64.png"/>
  <HighResolutionIconUrl DefaultValue="https://autodisc.vertexcs.com:86/Images/icon128.png"/>

  <SupportUrl DefaultValue="http://www.contoso.com" />
  <!-- Domains that will be allowed when navigating. For example, if you use ShowTaskpane and then have an href link, navigation will only be allowed if the domain is on this list. -->
  <AppDomains>
    <AppDomain>https://autodisc.vertexcs.com:86</AppDomain>
  </AppDomains>
  
  <Hosts>
    <Host Name="Mailbox" />
  </Hosts>
  <Requirements>
    <Sets>
      <Set Name="Mailbox" MinVersion="1.1" />
    </Sets>
  </Requirements>
  <FormSettings>
    <Form xsi:type="ItemRead">
      <DesktopSettings>
        <SourceLocation DefaultValue="https://autodisc.vertexcs.com:86/MessageRead.html"/>
        <RequestedHeight>250</RequestedHeight>
      </DesktopSettings>
    <PhoneSettings>
        <SourceLocation DefaultValue="https://autodisc.vertexcs.com:86/MessageRead.html"/>
    </PhoneSettings>
    </Form>
  </FormSettings>

  <Permissions>ReadWriteItem</Permissions>
  <Rule xsi:type="RuleCollection" Mode="Or">
    <Rule xsi:type="ItemIs" ItemType="Message" FormType="Read" />
    <Rule xsi:type="ItemIs" ItemType="Message" FormType="ReadOrEdit" />
  </Rule>

  <VersionOverrides xmlns="http://schemas.microsoft.com/office/mailappversionoverrides" xsi:type="VersionOverridesV1_0">
    <VersionOverrides xmlns="http://schemas.microsoft.com/office/mailappversionoverrides/1.1" xsi:type="VersionOverridesV1_1">
      <Requirements>
        <bt:Sets DefaultMinVersion="1.3">
          <bt:Set Name="Mailbox" />
        </bt:Sets>
      </Requirements>
      <Hosts>
        <Host xsi:type="MailHost">

          <DesktopFormFactor>
            <FunctionFile resid="functionFile" />

            <ExtensionPoint xsi:type="MessageReadCommandSurface">
              <OfficeTab id="TabDefault">
                <Group id="msgReadGroup">
                  <Label resid="groupLabel" />
                  <Control xsi:type="Button" id="msgReadOpenPaneButton">
                    <Label resid="taskPaneButtonLabel" />
                    <Supertip>
                      <Title resid="taskPaneButtonLabel" />
                      <Description resid="taskPaneButtonDescription" />
                    </Supertip>
                    <Icon>
                      <bt:Image size="16" resid="icon16" />
                      <bt:Image size="32" resid="icon32" />
                      <bt:Image size="80" resid="icon80" />
                    </Icon>
                    <Action xsi:type="ShowTaskpane">
                      <SourceLocation resid="messageReadTaskPaneUrl" />
                    </Action>
                  </Control>
                  <Control xsi:type="Button" id="msgReadActionButton">
                    <Label resid="actionButtonLabel"/>
                    <Supertip>
                      <Title resid="actionButtonLabel"/>
                      <Description resid="actionButtonDescription"/>
                    </Supertip>
                    <Icon>
                      <bt:Image size="16" resid="icon16"/>
                      <bt:Image size="32" resid="icon32"/>
                      <bt:Image size="80" resid="icon80"/>
                    </Icon>
                    <Action xsi:type="ExecuteFunction">
                      <FunctionName>defaultStatus</FunctionName>
                    </Action>
                  </Control>
                </Group>
              </OfficeTab>
            </ExtensionPoint>
          </DesktopFormFactor>

          <MobileFormFactor>
            <!-- Configures event-based activation. -->
            <ExtensionPoint xsi:type="LaunchEvent">
              <LaunchEvents>
                <LaunchEvent Type="OnNewMessageCompose" FunctionName="onNewMessageComposeHandler"/>
              </LaunchEvents>
              <!-- Identifies the runtime to be used (also referenced by the Runtime element). -->
              <SourceLocation resid="messageReadTaskPaneUrl"/>
            </ExtensionPoint>
          </MobileFormFactor>
        </Host>
      </Hosts>

      <Resources>
        <bt:Images>
          <bt:Image id="icon16" DefaultValue="https://autodisc.vertexcs.com:86/Images/icon16.png"/>
          <bt:Image id="icon32" DefaultValue="https://autodisc.vertexcs.com:86/Images/icon32.png"/>
          <bt:Image id="icon80" DefaultValue="https://autodisc.vertexcs.com:86/Images/icon80.png"/>
        </bt:Images>
        <bt:Urls>
          <bt:Url id="functionFile" DefaultValue="https://autodisc.vertexcs.com:86/Functions/FunctionFile.html"/>
          <bt:Url id="messageReadTaskPaneUrl" DefaultValue="https://autodisc.vertexcs.com:86/MessageRead.html"/>
        </bt:Urls>
        <bt:ShortStrings>
          <bt:String id="groupLabel" DefaultValue="My Add-in Group"/>        
          <bt:String id="taskPaneButtonLabel" DefaultValue="Show task pane"/>
          <bt:String id="actionButtonLabel" DefaultValue="Run Function"/>
        </bt:ShortStrings>
        <bt:LongStrings>
          <bt:String id="taskPaneButtonDescription" DefaultValue="Opens a task pane."/>
          <bt:String id="actionButtonDescription" DefaultValue="Click to run a sample function."/>
        </bt:LongStrings>
      </Resources>
    </VersionOverrides>
  </VersionOverrides>
</OfficeApp>

and uploaded to O365 admin for using it in Web application and mobile application, but Add-in is not showing in the Mobile application Add-in list.

I have tried clearing cache in the mobile app and also tried PowerShell Command

Set-OrganizationConfig -OutlookMobileGCCRestrictionsEnabled $false 

but it is not working.

My questions are:

• Have we missed anything after deployment or in the Manifest file?
• Do we need to run any other PowerShell commands to display the application in the Mobile Outlook Add-in list?
• In some forums it was mentioned that the Add-in needs to be Whitelisted, is there any such thing. If so, how to do that?

Please suggest us on how to proceed and help us with this manifest file (Add-in) to be working in the Outlook mobile application.