Last updated: May 2nd, 2022.
Users who have logged into multiple subdomains can experience issues logging into or interacting with meetings across domains. Interacting with multiple subdomains can cause incompatibility with the security tokens needed to verify your identity.
Common cases where an instructor would be logged into multiple subdomains:
Instructors with access to Class sandbox and then their school/org gets their own Class install
Demoing on multiple sandboxes
The solution is to log out of Class, log back in, and select the school you are trying to access.