UPDATE: This issue was fixed with the 1/25/2022 update.
Here is the Revision Note:
Issue: Aeries is aware of an issue with the SMS Board for Flex and Non-Flex schools occurring with the 1/18 update. While using the Add Class button, the Save attempt produces the spinning icon and the class does not add for the teacher.
Programming is looking into this issue and we will update this post when the issue is resolved.