Mordekaiser W bug

Yesterday while playing Mordekaiser in ARAM I encountered what I think is a bug on his W. The description for the ability made me believe that the ally I targeted with the W would be the one who would be affected by the ability but instead every time I used it, no matter who I clicked on, it simply affected the ally who was closest to me, as if I had been self-casting it the whole time (while I was in fact not self-casting). A little bit frustrating but mostly a minor annoyance for me but it seemed weird yet important enough for me to make a post about it here. I had just played Mordekaiser on Summoner's Rift the the day prior and encountered no issues, which is why this seemed out of the ordinary to me.

Gargalesthesia (my mains for each role :D)