If transforming into a Vampire Lord takes a lonnnnnnnnng time, it also isn't my mod at fault. You can also check out this page for bugs and solutions.
This can by fixed by entering the console and typing: set dlc1vampirelorddisallow to 0. Sometimes when you are made a Vampire Lord by either Harkon or Serana you will not be able to use the Vampire Lord power to turn into one. If you cannot transform into a Vampire Lord, it isn't my mod, but a game bug or conflict. My mod doesn't alter the original scripts for transforming and reverting at all.