Illaoi E bug with vessel.

I tried to get the recording of this match, but for some reason, Replay.gg doesn't have the one I needed, plus a few others. So basically, I was versing Darius top, & used E to rip his spirit out of him. I then commenced beating the hell out of it when Tryandmere arrived. The vessel was still very fresh, & tryand came in just as I started whaling on it. Darius's jungler Lee Sin came in, & it was a 2v2. I then watched my q, along with tryandmere, & a tentacle nearby hit his spirit for the killing blow, & then it traveled to Darius, & he recieved no slow, nor was he a vessel. His vessel even made the sound of a Dying Darius after it died. Afterwards, Tryand was kiting Lee Sin off, & Tryand died while I fought Darius. Lee Sin returned to help him get his kill, & Darius had barely anything in health. My tentacles by wall slammed down when I w'd, & even got my q's off flawlwssly, but in the end, I was a single hit away from killing him, & that could have easily been avoided, had he turned into a vessel LIKE HE WAS SUPPOSED TO. I asked Darius why he didn't turn into a vessel, & told him I'd post a recording of that spot, & that it was a bug. he didn't reply. Later, he says, "And to answer your question, it's not a bug, your tentacles only spawn on immobile objects like walls."After I pointed out that that wasn't the problem, & that it was him not turning into vessel, & slowing, he stayed silent. I hope I'm not the only one who's noticed this. I am well aware of the timer (Ring) around the spirit indicating the time I had.