Don't mind your question or questions anytime
Like you, I have given up trying to "lock" the sope aspect in MEP.
Usually, I have to draw the slope, measure the angle and then input the slope in MEP in degrees.
I am arranging for an on-line training session for MEP. So far I have listed:
slope piping/duct; clash detection; mark up tools and now that you ask about locking the slope preference, I will include it.
Let me know if you have another question, MEP or Archicad, and I will include it in the agenda.
BTW, you are in Campbell and I am in San Mateo, you are welcome to join me during this session; this is a first for me but Graphisoft convinced me it will save me time and efforts in the long run.
Win 10 Home Premium - AMD Phenom IIX6 1090T Processor 3.20 GHZ 8.00 GB RAM 64-bit Opp. Sys NVIDIA Quadro 4000 AC 22, MEP