[GAMEPLAY] Kalista's Black Spear glitched?

I was playing a ranked game earlier as Kalista. At the start of the game, I made Kayle my oathsworn using the Black Spear item given to Kalista automatically.

Well... Kayle went AFK. So I bought another Black Spear in the shop, and tried using it on other teammates to make them my new oathsworn.

When I clicked on any ally with the item, it made the bell sound, as it normally does, but then stopped, showed no animations, and did not do anything.

I was unable to use my ult for the remainder of the game since Kayle was still my oathsworn xD

Anyone else run into this problem? Are you able to change your oathsworn partner?

Edit: Tried in a custom game just now. Same thing. I try to use the item and it just goes on a 7 second cooldown.