Does anyone know if this is resolved or not? Since this bug was reported and ignored, geometa did add a directional force indicator arrow to the wing models in the workbench. If you had an aircraft with one wing oriented up and the other down, the indicator helps avoid this.
however, if the lift force is applied more to the left or right side of the wing section, you could only cancel it out by ensuring the wing sections are correctly mirrored, which the new indicator does not at all show.

This is very important bug report. Other wing components have this issue as well. Thanks for sharing.

I think more or less all of my planes are affected by this bug, that explains previously mysterious behavior.