Process variable history

Hi again!

Somehow the last completed task is not being listed with the described HistoricTaskInstance query.

The piece of code above is running within a delegate, which is being called by a final ServiceTask at the end of my process. It should generate a pdf document containing the list of executed User Tasks and their assignees, plus which fileds have been changed in each task. It works so far as expected. The only problem is that the last approval User Task in the process (Approve Application NPM or Approve Application NPM Delegated in the picture) is not being listed.

Could it be possible, that the history service needs some time to process changes, before I can query the final changes? Or could this be a bug?

I would appreciate any help very much.