I have fixed the problem. It turned out that there was somehow duplicate functions of 'bat_grades_overview' in the mdl_external_services_functions table in the DB. Deleting the duplicate brought everything back to normal.
Moodle for mobile
$mmSite: WS function 'bat_grades_overview' is not available, even in compatibility mode.
This discussion has been locked because a year has elapsed since the last post. Please start a new discussion topic.