Here are some possible solutions to the issue you are facing:

Check the URL configuration in the e-Learning module settings: Go to the e-Learning module settings and verify that the base URL is configured correctly. It should be set to [Odoo URL]/slides, which is the correct URL for accessing courses from the frontend. If the base URL is incorrect, update it and try accessing the course again from the backend.

Check the permissions of the course: Ensure that the user accessing the course from the backend has the appropriate permissions to view it. Check the Access Rights tab in the course settings to verify that the user has at least the "Read" permission. If not, update the permissions and try accessing the course again.

Check for any conflicting modules: There might be other modules installed in your Odoo instance that could be causing conflicts with the e-Learning module. Try disabling any other modules related to e-Learning or slides and see if the issue is resolved.

Check the Odoo logs: Check the Odoo logs to see if there are any error messages related to the e-Learning module or course access. If you find any errors, try to resolve them to see if that resolves the issue.

Hi,

Upon checking for the same in odoo runbot works fine for me, can you confirm whether this happens in runbot ? If not, it is something wrong with your instance, may be an not updated code or custom codes causing issue.

Can you check in runbot and see if it happens and try updating to your latest code.

Thanks