The marshaller works normally and nothing has changed with the last update so, it's not possible this would be caused by the update.
It will slide if you are looking at it from a too large distance and/or a too wide zoom settings, because FSX will automatically switch off all animations after a certain distance, and it has always been like this since GSX was released, since it's something we don't have any control over.
Also, if you noticed this only after a return flight, try to "Restart Couatl" before starting servicing on arrival, which usually fix the issue, in the rare occasions when it's not caused by the zoom/distance.