There is often confusion as to whether, when an aircraft is weighed, the empty weight includes unusable fuel. My understanding is that it does. (How would they get the unusable fuel out of the tanks for the weighing? Similarly the oil is included in the empty weight.) The thing to do is to enter the USABLE fuel as the capacity. I think the best way for this to be fixed in SD is to note this standard meaning of "empty weight" and to change the narrative on the fuel tank prompt from "capacity" to "usable fuel". The help on the field should provide or link to the empty weight definition.

Some fuel tanks have a considerable amount of unusable fuel. A related but off topic discussion is this: How is your dipstick calibrated? Usable or unusable?

Unfortunately there is no option to define the amount of dead fuel within the aircraft profile. The only way to do this right now is adding an additional w&b station including weight&arm of the unusable fuel. Reduce amount of max fuel capacity in the profile to usable & everything will be fine. Any plans to exclude dead fuel in future releases?