Ever since morphing the skill I have noticed that it tends not to last for it's full duration, furthermore upon ending the skill does not toggle off, so has to be manually toggled off in order to begin gaining ultimate again.
Even more disappointingly the game is not broken enough to think every kill while the skill is toggled on is a legitimate kill, advancing skill rank.
It could just have been that the server last night was screwing me around, but it coincides to closely with morphing it - and as the morph affects transform duration I can see that there may be a causal link.