Hi John,
This issue was posted to the Service Health Dashboard (SHD) as incident TM204302starting at **2020-02-20 22:30:53 (UTC).**The user experience of this incident is: Users may not be able to select emojis or reactions in the Microsoft Teams desktop and web clients. Tenant administrators can view current information and updates on SHD at the link here
https://portal.office.com/admin/default.aspx#@/ServiceStatus/ServiceStatusHistory.aspx.
For affected customers to easily identify the information here, this thread will be closed.
We will update to the primary thread below once the issue is resolved or you can obtain the most recent information from SHD:
Best Regards,
Sylvie