Hi NamritaK,
Thank you for posting your question in this community. From your description and screenshot, the Class Notebook in Teams for the web application cannot save your works after you finish your editing.
First of all, I strongly suggest you back up your works to other location, such as Word document, notepad, before you take any further action to avoid any data lost.
After that, I suggest you can try to update your work though OneNote for the web and see the result.
1: You can log into to OneNote for the web with your school account.
2: Go to Class notebooks tab to open this class notebook

3: Check whether your works have been updated there. If not, copy and paste the works to this notebook and see whether it can be updated successfully.
Best regards,
Dihao