Tahm Kench W bugged.... still

Just like the title says. Cannot devour ally champion. This has been a problem for so long too. I don't know what causes it. All I can say is that I was playing a game w/ a Project Lucian ally that I could not cast W on. Didn't matter if smart cast was enabled or not. Reset did not resolve issue. Worked fine on everyone else except for the one target I actually I needed to save. Very frustrating having such a key ability be of no use.