The page for "Torment of Destiny" at New Voyages: Phase II, International gives an official statement on why production was halted.
Update Feb. 2018: Due to the CBS Fan-Film Guidelines, post-production work on this episode has been halted. All scenes have been filmed, but there are about 180 visual effects that need to be added to the episode, which would be many months of work. As two of our three visual effects experts can no longer work on the project due to the restrictions of the Fan-Film guidelines, completion of this episode cannot continue without special permission being granted from CBS. This is unlikely during release of Discovery and we are unsure if this episode will ever be permitted to be completed. We understand this is disappointing for our loyal fans, but we are not responsible for the events that led up to the release of those guidelines.
https://www.stnv.de/en/4x11_torment_of_destiny.php