Steps to reproduce:

1. Create contract
2. Assign assistants to user "admin" via "Orgstructure" tool
3. Send to approval: 1st and the only stage - admin
4. Go to contract card (being logined as "admin" user)
5. Press "I'll perform this" button at confirm task cardlet
6. Renew current page

Expected result: 2 buttons "Back to shared pool" and "Reassign" (and no other buttons) will be shown at task cardlet
Actual result: 2 buttons "I'll perform this" and "Back to shared pool" (and no other buttons) will be shown at task cardlet

7. Press "Back to shared pool" button at confirm task cardlet
8. Renew current page

Expected result: 1 button "I'll perform this" (and no other buttons) will be shown at task cardlet
Actual result: no task cardlet shown at doc page, tasks cardlet (right top part of page): confirm task is shown, but has no pool

Similar behaviour noticed at all tasks assigned to 1 user which has 1 or more assistants.