Yeah, slope FOFs are tricky like that. It's all about where you place the control sector relative to the target sector. Imagine the control sector's slope as extending in all directions including to the target sector, and it might make sense why it appears in the wrong place?
In any case, a simple way to fix this depends on which direction your slope goes up/down: If it's supposed to go up in the West or East directions, simply place your control sector North or South of the target sector. Likewise, if the slope is supposed to go up in the North or South directions, place the control sector West or East of the target sector.