Invalid history_process task

[aspark21]

Moodle 4.2

Got to your.moodle.site/admin/tool/task/adhoctasks.php?classname=%5Clocal_assessfreq%5Ctask%5Chistory_process
The following error occurs:
Invalid task class \local_assessfreq\task\history_process

This seems to affect & prevent processing of other ad-hoc tasks in that test site
It may also explain other issues we've had in having the dashboard display all of the historical data in 3.11 (seeing as this view of ad-hoc tasks is only available in moodle 4.x) but maybe unrelated to this