I think this is a bug or rather an incompleteness in the implemenation of MDL_10965 and there are others (as in this discussion: https://moodle.org/mod/forum/discuss.php?d=431270#p1735828).
I think opening a new ticket to get some fixes for this would be a good first step.
I think opening a new ticket to get some fixes for this would be a good first step.