When defining standard RC members (i.e not user defined sections from section builder) with non-symmetrical sections (for instance "L" shape sections) then the local coordinate system follows its sides and not the principle axes of the section (the opposite is for a section created in section builder that has its LCS according to the principle axes, but in this case there is no design procedure in Robot).
This causes inaccuracies in the results.
At least, it should be as it is for steel members that users can chose between pinciple axes or not.