I'm having the same issue with AC18. I tried to search for a solution and found this thread.
To me it seems that the Built-in Section Marker works fine, but the NCS markers don't. They are horizontal to the absolute 0 but not to the relative (view) 0. We could be using the built-in marker for building sections, but we need the NCS partial section marker for wall sections, so I can't figure out a good work-around at the moment. Too bad, because these are markers that come with the box. Hopefully AC19 and 20 has this solved...
macOS 15, ArchiCAD 26/27/28 (USA)
first ArchiCAD: 6.5