Adding FAQ for portal errors

We had a wave a support cases opened because Transaction Search page had error retrieving data. All customers were using the same 3rd party browser extension which was blocking the API calls from browser to App Insights. We need to provide guidance on how customers can diagnose and troubleshoot these issues on their own for very common azure portal issues we see while navigating Application Insights resources. This "error retrieving data" message shows up on tx search, performance, overview and other blades if we fail to call the APIs. All of these issues are typically client network or browser extension related. This FAQ should help customers diagnose the issue on their own.

Author: toddfoust

articles/azure-monitor/app/transaction-diagnostics.md

@@ -104,3 +104,7 @@ In these scenarios, you can use Automatic Route Tracking to automatically create
 Time not explained in the Gantt chart is time that isn't covered by a tracked dependency. This issue can occur because external calls weren't instrumented, either automatically or manually. It can also occur because the time taken was in process rather than because of an external call.
 
 If all calls were instrumented, in process is the likely root cause for the time spent. A useful tool for diagnosing the process is the [Application Insights profiler](./profiler.md).
+
+### What if I see the message ***Error retrieving data*** while navigating Application Insights in the Azure portal? 
+
+This error indicates that the browser was unable to call into a required API or the API returned a failure response. To troubleshoot the behavior, open a browser [InPrivate window](https://support.microsoft.com/microsoft-edge/browse-inprivate-in-microsoft-edge-cd2c9a48-0bc4-b98e-5e46-ac40c84e27e2) and [disable any browser extensions](https://support.microsoft.com/microsoft-edge/add-turn-off-or-remove-extensions-in-microsoft-edge-9c0ec68c-2fbc-2f2c-9ff0-bdc76f46b026) that are running, then identify if you can still reproduce the portal behavior. If the portal error still occurs, try testing with other browsers, or other machines, investigate DNS or other network related issues from the client machine where the API calls are failing. If the portal error persists and requires further investigations, then [collect a browser network trace](https://learn.microsoft.com/azure/azure-portal/capture-browser-trace) while you reproduce the unexpected portal behavior and open a support case from the Azure portal.