title: Two UpdatePanels working in parallel, one not updating
body: <p>I have two update panels (lets call them A and B). In A, I have a simple checkbox. AutoPostback set to true. When you check it (or uncheck it), it will enable/disable a simple dropdown within the same UpdatePanel.</p>
  
  <p>UpdatePanel B has a long running process in it. It fires off a request for a dropdown to be created that takes nearly 2 minutes to construct. If I load the page and don't touch anything, the dropdown is constructed after about 2 minutes and renders perfectly. However, if during that two minutes I decide to check my checkbox (and cause a partial postback for panel A), updatepanel B never gets rendered. While debugging, I found that it is completing its retrieval successfully, but the actual panel never refreshes to show the control.</p>
  
  <p>I have tried using UpdateMode = Conditional on panel B (to ensure it would not be disturbed by panel A) and it produces the same results. I have verified that B.Update() is being called also.</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>Panel A:</p>
  
  <pre><code>&lt;asp:UpdatePanel ID="upMailScrub" runat="server"&gt;
      &lt;ContentTemplate&gt;
          &lt;asp:Button ID="btnAnalyzeLaunch" runat="server" onclick="btnAnalyzeLaunch_Click" Text="Analyze Launch" style="display: none" /&gt;    
          &lt;table&gt;
              &lt;tr&gt;
                  &lt;td&gt;&lt;asp:CheckBox ID="cbxScrub" runat="server" Checked="true" 
                          oncheckedchanged="cbxScrub_CheckedChanged" AutoPostBack="True" /&gt;&lt;/td&gt;&lt;td&gt;&lt;label for="cbxScrub"&gt;Scrub this campaign&lt;/label&gt;&lt;/td&gt;
                  &lt;td style="padding-left: 10px"&gt;
                      Vendor:&amp;nbsp;&amp;nbsp;&lt;asp:DropDownList ID="ddlScrubVendor" runat="server"&gt;
                          &lt;asp:ListItem Text="LexisNexis" Value="LexisNexis" /&gt;
                      &lt;/asp:DropDownList&gt;
                  &lt;/td&gt;
              &lt;/tr&gt;
          &lt;/table&gt;
      &lt;/ContentTemplate&gt;
  &lt;/asp:UpdatePanel&gt;
  </code></pre>
  
  <p>Panel B:</p>
  
  <pre><code>&lt;asp:UpdatePanel ID="upDdlCampaigns" runat="server" UpdateMode="Conditional"&gt;
      &lt;Triggers&gt;
          &lt;asp:AsyncPostBackTrigger ControlID="btnAnalyzeLaunch" EventName="Click" /&gt;
      &lt;/Triggers&gt;
      &lt;ContentTemplate&gt;
          &lt;asp:HiddenField id="hidAction" runat="server" /&gt;
          &lt;asp:Panel ID="pnlPleaseWait" runat="server"&gt;&lt;img src="style/images/PleaseWait.gif" /&gt;&amp;nbsp;Please wait while the Five9 Campaigns are retrieved...&lt;/asp:Panel&gt;
          &lt;asp:DropDownList ID="ddlCampaigns" Visible="false" runat="server" class="required"
              AutoPostBack="True" OnSelectedIndexChanged="ddlCampaigns_SelectedIndexChanged" /&gt;
          &lt;asp:Button ID="btnRefreshDDL" runat="server" onclick="btnRefreshDDL_Click" style="display: none" /&gt;
      &lt;/ContentTemplate&gt;
  &lt;/asp:UpdatePanel&gt;
  </code></pre>
  
  <p>Any suggestions? Thanks.</p>