Using Classic Outlook on Windows for personal email, calendar, and contact management
Hello Phuc Le HPE,
1.Please which Office 365 version the affected user is using?
2.please can you confirm if the add-in icon appears on the ribbon of outlook app? if not relaunch Office to see the add-in icon appear on the ribbon of app. wait for 12 hours and then check whether the add-in appears on the ribbon and your Services & add-ins list.
3.please check if you can see the add-in in Exchange admin center > organization > add-ins. ask the affected user to ask the global admin or his IT department.
- I want to check the "FindTime" Add-in using Windows PowerShell, please let me if you can access easily, you admin portal or contact your global admin
In the meantime, ask the user to use another computer not yours, to see if the issue still persist
Please get back to us with necessary information, we’ll be glad to assist you further.
Appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely,
Eben Ezer Tres | Microsoft Community Moderator