A teacher could not save a quiz. The message appears: "You must fill in the feedback boxes without leaving any gaps"
We tried it with FF, Chrome and Edge. Always the same message.
If I changed the editor to TinyMCE it worked. It has something to do with the Atto editor ore a plugin for the Atto editor.
Moodle 3.3.2+ (Build: 20171027)
The same problem is discussed https://moodle.org/mod/forum/discuss.php?d=180728