In debug mode, this error is displaying when submitting attendance form (by teacher) :
Argument $record must be an instance of stdClass.
- line 784 of /lib/classes/event/base.php: call to debugging()
- line 970 of /mod/attendance/locallib.php: call to core\event\base->add_record_snapshot()
- line 56 of /mod/attendance/take.php: call to attendance->take_from_form_data()
However, it seems to work ...