>> Not sure what GoTo Auto-Center does?
Depending on how precisely you have done an initial polar and star alignment, and the quality of the equatorial mount, a plate solve and goto can land you a little off the target object.
What you usually had to do was to repeatedly execute a number of plate solves and gotos to zero in to the object.
When you turn on auto-center, ASIAIR will do a series of exposure/plate-solve/goto for you.
Chen