Outlook外接程序可在Outlook Online中使用，但不会显示在Outlook客户端中

Question

最近，我开发了一个Outlook加载项，它将具有两个下拉按钮和一个任务窗格按钮。外接程序在Outlook Online中正常工作。但是，外接程序不会显示在Outlook客户端功能区中。

如果我从加载项中删除下拉菜单按钮之一，则在所有环境中都可以正常工作。

我读到，目前仅允许一个级别的下拉列表，但与下拉列表的数量无关。清单中使用的下拉控件的数量是否有限制？

我在Office 365 Pro Plus上运行，并且Outlook客户端版本为1804（内部版本9226.2114）

我正在使用VersionOverridesV1_0及以下控件：

        <OfficeTab id="TabDefault">

          <Group id="msgReadGroup">
            <Label resid="groupLabel" />

            <Control xsi:type="Menu" id="msgReadMenuButton">
              <Label resid="msgReadMenuLabel" />
              <Supertip>
                <Title resid="msgReadMenuLabelTitle" />
                <Description resid="msgReadMenuSuperTipDescription" />
              </Supertip>
              <Icon>
                <bt:Image size="16" resid="mail16" />
                <bt:Image size="32" resid="mail32" />
                <bt:Image size="80" resid="mail80" />
              </Icon>
              <Items>
                <Item id="Item1">
                  <Label resid="Item1Label"/>
                  <Supertip>
                    <Title resid="Item1LabelTitle" />
                    <Description resid="Item1SuperTipDescription" />
                  </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>Function1</FunctionName>
                  </Action>
                </Item>

                <Item id="Item2">
                  <Label resid="Item2Label"/>
                  <Supertip>
                    <Title resid="Item2LabelTitle" />
                    <Description resid="Item2SuperTipDescription" />
                  </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>Function1</FunctionName>
                  </Action>
                </Item>
              </Items>
            </Control>

            <Control xsi:type="Menu" id="meetingReadMenu">
              <Label resid="meetingReadLabel" />
              <Supertip>
                <Title resid="meetingReadMenuTitle" />
                <Description resid="meetingReadMenuSuperTipDescr" />
              </Supertip>
              <Icon>
                <bt:Image size="16" resid="icon16" />
                <bt:Image size="32" resid="icon32" />
                <bt:Image size="80" resid="icon80" />
              </Icon>
              <Items>
                <Item id="meetingItem1">
                  <Label resid="meetingItem1Label"/>
                  <Supertip>
                    <Title resid="meetingItem1Title" />
                    <Description resid="meetingItem1SUSuperTipDescr" />
                  </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>Function1</FunctionName>
                  </Action>
                </Item>
                <Item id="meetingItem2">
                  <Label resid="meetingItem2Label"/>
                  <Supertip>
                    <Title resid="meetingItem2Title" />
                    <Description resid="meetingItem2SuperTipDescr" />
                  </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>Function1</FunctionName>
                  </Action>
                </Item>
                </Items>
              </Control>


            <Control xsi:type="Button" id="taskpaneButton">
                <Label resid="taskpaneButtonLabel" />
                <Supertip>
                  <Title resid="taskpaneButtonTitle" />
                  <Description resid="taskpaneButtonSuperTipDescr" />
                </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="readTaskPaneUrl" />
                </Action>
              </Control>

            <Control xsi:type="Menu" id="ReadMenuButton">
              <Label resid="ReadMenu" />
              <Supertip>
                <Title resid="ReadMenuSuperTipTitle" />
                <Description resid="ReadMenuSuperTipDescription" />
              </Supertip>
              <Icon>
                <bt:Image size="16" resid="help16" />
                <bt:Image size="32" resid="help32" />
                <bt:Image size="80" resid="help80" />
              </Icon>
              <Items>
                <Item id="ReadItem1">
                  <Label resid="ReadItem1Label"/>
                  <Supertip>
                    <Title resid="ReadItem1Title" />
                    <Description resid="ReadItem1SuperTipDescr" />
                  </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>Function1</FunctionName>
                  </Action>
                </Item>

                <Item id="ReadItem2">
                  <Label resid="ReadItem2Label"/>
                  <Supertip>
                    <Title resid="ReadItem2Title" />
                    <Description resid="ReadItem2SuperTipDescr" />
                  </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>Function1</FunctionName>
                  </Action>
                </Item>
              </Items>
            </Control>                 
            <!-- Go to http://aka.ms/ButtonCommands to learn how to add more Controls: ExecuteFunction and Menu -->
          </Group>
        </OfficeTab>
      </ExtensionPoint>