devtrackers.gg
The only thing i can think of is the fury tried to walk through your tower for a brief sec because it had aggro on someone, and it probably has priority over player walls so it canceled the 'wall' that is the ult. and then promptly lost all aggro and went back to it's spawn.
I know the titan, for example, will end a ymir wall early if they collide so the titan can path through it so I assume the fury must have some similar pathing priority system.