Maybe the TryGetPawnOwner is resulting in IsNotValid. In such a case, the speed won’t be calculated. The blendspace will receive 0 as speed and the character will continue to stay in idle animation.
Try attaching a PrintString to IsNotValid exec node to confirm this.
Additionally, try doing this. Instead of calling TryGetPawnOwner every frame, store the value in a variable when the AnimBP is initialized. I am not sure if this could be the problem, but no harm in testing it out, right? 
