You're sure that your planter isn't dropping seed when it's over the un-planted area? If you have hydraulic drive in the planter setup menus there is the option in there to set the height where the drive turns on and off. This is so that you can have the planter dropping seed before it's all the way down so you don't have a delay.

In the 2600, under the implement setup tab, the recording source should be set to "AUTO" and greyed out so that you can't change it. If it isn't, you have something setup wrong......possibly you don't have an implement defined correctly.