All models, all serial numbers. This affect is normally experianced when using the voltage type analog input.
These drives have floating power supplies. Therefore, instability of the signal can occurr if conducted or radiated noise is coupled to the wires connected to the analog input.
One resolution for all of these drives is to connect the common terminal (COM) to chassis ground. For ATV61 and ATV71 drives if connecting the common to chassis ground does not eliminate the problem set the AI1 filter (AIIF) parameter. This setting can be adjusted between 0 and 10 seconds.