Median is with more than 10 frames alwyas inferior to average stacking Vincent, so I would suggest only to use median with just a couple of frames. Have you applied bias or darks, or a BPM in calibration?
Why use no normalization? Normalization is actually an essential part of stacking. Or did you mean bacgkround neturalization? If you are working with monochrome data, like you do, this setting has no influence. It only applies to RGB data.