Its been an issue people have complained about since it was released in season 2. It would be nice if it was fixed at some point, but we are now what 2 seasons from its release with no fix, hope is not strong at this point.
I’d guess if it’s registered as an issue on Blizzard’s end, its fairly far down on the list of things to fix as its not preventing the game from running or otherwise wrecking havoc. Its likely a case of property field pointing to the wrong animation file by mistake, or maybe they just pointed it to the Invincible dash file as they didn’t make one for this cosmetic?