Forwarding in Workflow Task does NOT work

Hi all

I have WorkFlow with User Decision step. It uses standard WorkFlow task TS00008267 whis is General Task. But I could not forward this task in SBWP transaction. (Screen #1)

I also could not reassign WorkFlow task using SWIA transaction to any staff  (Screen #2).

I could not do that not  only with User Decision step but with Activity step as well.

Is anybody know what can be a reason of that ?