By what you said I think its the model's fault.
While the AURA follows normally and effects at the correct range, the graphics are "lagging" behind, probably because it is a particle based model. (or something. not an good modeler so I don't know the terms for everything.)
Trying switching a model to a normal aura and check if it works properly, if it does then its jest a graphic situation cause by the fact the model you have makes use of free partials who have their own path once they left the origin, and therefor does not even "know" the hero moves, whoever the effect itself is as normal.