Question:
On closer inspection of the results, I noticed that the moment distributions in columns point in different directions or change signs.
Answer:
You should always pay attention to the member orientation and rotation when defining columns consisting of several individual members. Some members have the x-axis directed upwards or rotated (see Image 01). Due to different orientations, the sign changes for My or Mz.
You can check these settings easily by activating the display of member axis systems (see the image).