Localization issue in OWA where ribbon's DisplayName & Description always fall back to DefaultValue

[Grivj]

Your Environment

• Platform: OWA
• Host Outlook
• Operating System: Mac (26.2)
• Browser: Chrome
• User language: French (OWA UI set to French)

Expected behavior

We understand that Supertip Description may not be supported on OWA, but we still expect at least:
• <Label resid="..."> localized via bt:ShortStrings + bt:Override
• <Supertip><Title resid="..."> localized via bt:ShortStrings + bt:Override
In other words, when the UI language is French, we expect the command label and tooltip title to show the fr-FR override values instead of the DefaultValue.

Current behavior

In OWA, the UI entry shown in the add-ins/apps command surface continues to display only the DefaultValue strings (English) and never the fr-FR overrides. Adding <Supertip> does not change this: neither Title nor Description are used.

However, the same manifest’s root / overrides do appear localized in the “installed add-ins” / manage add-ins view:

Steps to reproduce

1. In OWA, set language to French (or any other language that's not the manifest's default locale)
2. Install the add-in using the manifest below
3. Show the add-ins UI surface where add-ins are listen (cf. first screenshot)
4. Observe the label/tooltip: it keeps showing the DefaultValue strings instead of the fr-FR (or fr-fr, tried both and same behavior) overrides.

Minimal repro manifest

Here's the full simplified manifest we've been testing with:

<?xml version="1.0" encoding="UTF-8"?>
<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"
  xsi:type="MailApp">

  <Id>00000000-0000-0000-0000-000000000000</Id>

  <Version>1.0.0.0</Version>
  <ProviderName>Example</ProviderName>
  <DefaultLocale>en-US</DefaultLocale>

  <DisplayName DefaultValue="DisplayName.DefaultValue">
    <Override Locale="fr-FR" Value="DisplayName.fr-FR" />
  </DisplayName>

  <Description DefaultValue="Description.DefaultValue">
    <Override Locale="fr-FR" Value="Description.fr-FR" />
  </Description>

  <IconUrl DefaultValue="https://example.com/assets/icon-64.png" />
  <HighResolutionIconUrl DefaultValue="https://example.com/assets/icon-80.png" />
  <SupportUrl DefaultValue="https://example.com/support" />

  <AppDomains>
    <AppDomain>https://example.com</AppDomain>
  </AppDomains>

  <Hosts>
    <Host Name="Mailbox" />
  </Hosts>

  <Requirements>
    <Sets>
      <Set Name="Mailbox" MinVersion="1.3" />
    </Sets>
  </Requirements>

  <FormSettings>
    <Form xsi:type="ItemRead">
      <DesktopSettings>
        <SourceLocation DefaultValue="https://example.com/taskpane.html" />
        <RequestedHeight>300</RequestedHeight>
      </DesktopSettings>
    </Form>
  </FormSettings>

  <Permissions>ReadItem</Permissions>

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

  <DisableEntityHighlighting>false</DisableEntityHighlighting>

  <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>
            <ExtensionPoint xsi:type="MessageReadCommandSurface">
              <OfficeTab id="TabDefault">
                <Group id="msgReadGroup">
                  <Label resid="GroupLabel" />

                  <Control xsi:type="Button" id="OpenTaskpaneButton">
                    <Label resid="Button.Label" />

                    <Supertip>
                      <Title resid="Button.SupertipTitle" />
                      <Description resid="Button.SupertipDescription" />
                    </Supertip>

                    <Icon>
                      <bt:Image size="16" resid="Icon.16" />
                      <bt:Image size="32" resid="Icon.32" />
                      <bt:Image size="80" resid="Icon.80" />
                    </Icon>

                    <Action xsi:type="ShowTaskpane">
                      <SourceLocation resid="Taskpane.Url" />
                    </Action>
                  </Control>

                </Group>
              </OfficeTab>
            </ExtensionPoint>
          </DesktopFormFactor>
        </Host>
      </Hosts>

      <Resources>
        <bt:Images>
          <bt:Image id="Icon.16" DefaultValue="https://example.com/assets/icon-16.png" />
          <bt:Image id="Icon.32" DefaultValue="https://example.com/assets/icon-32.png" />
          <bt:Image id="Icon.80" DefaultValue="https://example.com/assets/icon-80.png" />
        </bt:Images>

        <bt:Urls>
          <bt:Url id="Taskpane.Url" DefaultValue="https://example.com/taskpane.html" />
        </bt:Urls>

        <bt:ShortStrings>
          <bt:String id="GroupLabel" DefaultValue="GroupLabel.DefaultValue">
            <bt:Override Locale="fr-FR" Value="GroupLabel.fr-FR" />
          </bt:String>

          <bt:String id="Button.Label" DefaultValue="Button.Label.DefaultValue">
            <bt:Override Locale="fr-FR" Value="Button.Label.fr-FR" />
          </bt:String>

          <bt:String id="Button.SupertipTitle" DefaultValue="Button.SupertipTitle.DefaultValue">
            <bt:Override Locale="fr-FR" Value="Button.SupertipTitle.fr-FR" />
          </bt:String>
        </bt:ShortStrings>

        <bt:LongStrings>
          <bt:String id="Button.SupertipDescription"
            DefaultValue="Button.SupertipDescription.DefaultValue">
            <bt:Override Locale="fr-FR" Value="Button.SupertipDescription.fr-FR" />
          </bt:String>
        </bt:LongStrings>
      </Resources>

    </VersionOverrides>
  </VersionOverrides>

</OfficeApp>

Is it expected that the OWA surface shown in the screenshot ignores bt:Override localization for command Label / Supertip Title and always shows DefaultValue? If not expected, is this a known bug/regression, and is there a recommended workaround other than hardcoding localized text in DefaultValue?

Thanks.

[github-actions]

Here are some similar issues that might help you. Please check if they can solve your problem.

• The add-in's <Description> of the main ribbon doesn't get overridden by its locales #5931

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[Grivj]

Here are some similar issues that might help you. Please check if they can solve your problem.

*

This issue and the remediation has been taken into account but without success :(
Are we missing something in the manifest that would explain this behavior?

[nbaliga18]

Thanks for reporting this issue and for providing a minimal repro.

Routing this to the PowerPoint add-on team for investigation.
Assigned to: @jonahkarpman

[Grivj]

Thanks for reporting this issue and for providing a minimal repro.

Routing this to the PowerPoint add-on team for investigation. Assigned to: @jonahkarpman

Thanks for the quick reply, small clarification though: this repro is an Outlook add-in and the issue is observed specifically in OWA, there's no PowerPoint host involved on our side.

If the PowerPoint add-on team is still the right owner, totally fine! I just wanted to make sure it doesn't get mis-triaged as a PowerPoint-specific problem 🙏