Salesforce for Outlook - Side Panel fails to load when Lightning for Outlook is used
|Knowledge Article Number||000230218|
|Description||If a user is using both Lightning for Outlook (SAFO) and Salesforce for Outlook (SFO) the default behavior is for the SFO Side Panel to disconnect and not display. One main indicator would be the existence of the "Add Email" button on your Outlook toolbar. If you have the Side Panel option enabled the Add Email button should not load
To check if the user is using Lightning For Outlook:
In Classic View
In Lightning Experience
On the local machine checking the "AddinTrace.log" file in the Salesforce for Outlook logs should also show the lines below if the user is an active Lightning for Outlook user.
DEBUG adxsidepanel  UnsafeInvokeInternal : Updating Side Panel... DEBUG adxsidepanel  InvokeMethod : Ignored because config is disabled**Salesforce for Outlook - Location of Log Files**