If the course element Check list is used with more than one group there is a critical bug.
2 Users in the course using the check list element. (picture Bug1.jpg)
1 User is in Group "Testgruppe" and 1 user is not (Bug2.jpg)
If you filter to "Testgruppe" and use the edit function (Bug3.jpg) after saving and deactivating the filter, all previously checked boxes from users not in the filtered group are deleted (Bug4.jpg).
This problem is reproduceable in ALL OLAT versions starting from the implemention of the checklist with OLAT 9.4.