Are the quizzes metaboxes mising from your Sensei LMS lessons pages after updating to the version There is a really quick fix which is simply to activate the Classic Editor plugin.

If that doesn’t work you probably have version installed. In that case simply update the plugin to or later and install the Classic Editor.

The reason behind the issue is that Sensei LMS has started using Gutenberg blocks to create quizzes, which now seems to be the new standard method. However for Page Builder users this doesn’t make sense, so luckily the legacy metaboxes can easily be activated again by using the Classic Editor.