[Gameplay] Vi Ult Mis-targetting and Positioning

On summoner's rift. Playing as Vi, utilizing Assault and Battery ("While charging, Vi is Immune to crowd control"). Attempted ulting enemy Fiddlesticks who was beyond enemy Nasus in the line of Vi's ultimate.

Vi's ult acted like it targeted Fiddlesticks, went through roughly half of the ult animation, then Vi returned to her starting point of the ult initiation. Upon returning, the target ended up as Nasus; Vi repositioned to the position of Nasus.

Fiddlesticks ------- Nasus ------- Vi

I've encountered other instances of Vi's ult being interrupted when it shouldn't have (ie abilities that would not normally interrupt her ult in the past). The most recent and clear memory I have is when Fiddlesticks was able to fear Vi in different instance during Vi's ult animation.