Thank you for your question and I am sorry about the issue!
Unfortunately, I'm not an expert in either MEP or GDL, so I cannot tell which problem this is. If this is a GDL issue, have you checked out the GDL Forums? This is the specialized forum for GDL experts, so you may receive a quicker answer there!
But if you believe this is an MEP issue, please let me know, and I will forward this to our colleagues to have a closer look!
May be there is a way to find as I have found it "MEP_m_ConnectionsACL_4" macro
Open the 3D script of the "Dryer" library part
Object Subtype HAS to be something more specific for the macro to work.
That was the only mistake. As i changed it to "Flow Terminal" it started working right away. (I got an answer at the old GDL forum). I had it set as "Flow Device".
I wish that the GDL center had better MEP examples/ instructions, makes it harder than has to be. I even learned to used LP2XML converter to create 144 MEP connection parameters and not having to write them on the object interface itself. Really happy with VSCode new template by the way!
Regarding LP2XML converter, this one also deserves a better help page.
Archicad User Since 2013
Experimenting with API