Due to the release of Schoolbox v21.0.0, your remote services module requires that 3rd party sites, such as EdSmart, being embedded into Schoolbox are allowed via the safe iframe sites list.
This is to prevent some forms of phishing and XSS attacks. This list can be edited in Admin -> System Settings -> Security (Safe Iframe Sites).
Schools using the EdSmart integration must add ‘app.edsmart.com’ to the list per the below screenshot.
If you are still having issues please contact the EdSmart HelpDesk or help@edsmart.com