Hi Ian,

AutoCAD always create .BAK filed on each save in the folder where the drawing you are editing is located (if ISAVEBAK sys var equals 1 - the default value OOTB)

So you mean Autosave location.

Can you verify settings in AutoCAD preferences?

Do you have Autosave enabled? - look at "General tab"

Have you tried to change Autosave path in AutoCAD preferences?