"Same ingredients, same technique."
If you are brewing the same recipe and using the same technique, then I would suspect that this represents your process variability and/or measurement error. How well can you measure your volumes going in and coming out? Have your brew kettle and fermenter been measured and marked for volumes? This is usually the biggest area of measurement error for most brewers. I would not trust factory marked volumes as they are usually etched and added based upon a set template and do not take into account variations from piece to piece.
For your brew last night, 6 gravity points for how much volume? Also, if you used only 4 oz of flaked wheat and 4 oz of flaked oats I would suspect that you may have measured some gravity, but it would be starch and not sugars. The flaking process for grains brings the grains up to gelatinization temperatures and presses them to make the starches more accessible, but do NOT convert those starches to sugar. In order to do this, you need a base malt to provide the enzymes needed to reduce the starches to sugars.
In the end, if you have converted malts (crystal, caramel, biscuit, brown, chocolate, black, roasted) then you can steep them and use extract settings. If you have base malts or malts that need to be mashed (the description of each malt lists a "MUST MASH" as either 'true' or 'false'. Malts marked as 'true' must be mashed to give you any fermentable sugars.) then use the partial mash settings. If you find that the settings don't match your results, then you need to focus on tuning in the settings in your equipment profile to match your actual values. Switching back and forth trying to explain your variability is not solving your problem, it is only causing you confusion and hiding the issues you need to address.