Cancel Task does not terminate execution in Workflow Designer

Scenario:
After fix UGENE-7224 some problems were detected:

1. Long execution is performing on the big data, more than 16 minutes.
2. Select and expand Task section
3. Select "Map to reference" and select "Cancel Task" from context menu
   Expected state: End of execution
   Actual state: No any reaction
4. Close WD window
5. Click Discard in question "The Workflow has been modified. Do you want to save changes?"
   Expected state: End of execution
   Actual state: No any reaction
6. File->Exit
7. Click OK in Shutdown confirmation dialog
   Expected state: End of execution
   Actual state: No any reaction. Possible to termibate task via Task manager only