Royann- By your screenshot, it looks like you are using the Outlook App, not the Add-In.
I encountered a similar issue recently, but am on version 9.2 of CRM. (I highly recommend the update as it brings a lot of new features and functionality to the App!). Anyway, this is the Microsoft instructions to clear the cache. This worked for me, as it seems to be specific to the user, not the Admin settings. However, I am not sure how often this may come back since it is a cache issue?1. Launch Outlook on your desktop and click on Dynamics 365 app from the Outlook ribbon on top.2. Go to File Explorer -> C drive -> Windows Folder -> System32 -> F12 -> IEChooser.exe3. Once you open IEChooser, you will find Click on Dynamics 365 thread4. Go to Network tab and click clear cache button on top.5. Try to perform search in Dynamics 365 App for Outlook after few minutes of clearing the cache.Hope this helps?Ron