Symptoms

Suppose you have the following situation: There is a group approval task event in workflow with SharePoint group set as its destination. Initially this task is being displayed as “Available” to all users from the destination SharePoint group. Next, one of the group members opens this task – task becomes “Allocated” for all the other users within group (expected behavior) and “Open” for user who opened it. Next, this user tries to release this task and expected behavior is that all the other users should be able to see this task as “Available” again, but what actually happens is that task stays “Allocated” for all of the users apart from one who released it.
 

Diagnoses

There is a known issue with task slot recalculation when worklist-item release operation does not work with K2 role or group destination.

Another symtom/problem you may see because of this is whenu you use K2 role as a destination for worklist-item you may notice that it is not possible to release this item from administrative worklist in K2 workspace.

As a workaround which can be used to address this task release issue it is possible to change the destination rule configuration so that it has the following settings:

Plan per destination - All at once
Resolve all roles and groups to users
 

Note: when switching activity destination rule to  ‘Resolve all Roles and groups to users’ it is expected behavior for all events placed in this activity to be triggered triggered as many times as the number of users in the role while it is not necessary. In case you have events which not supposed to be triggere multipletimes you have to split them into separate activity. And in general you should always split user tasks and server tasks in separate activities.

Resolution

To resolve this issue change destination rule configuration as follows:

Plan per destination - All at once
Resolve all roles and groups to users