solution (of sorts)
  It appears that some library parts, are used by Mep Modeler -- with a different icon,   as long as I use them
as normal library parts they work fine - If they show a "cabinet" icon then they start looking for a mep modeler key .
					
				
			
			
				
	ArchiCAD 4.5 --- 27 , Win 10 , dual monitors, 64 gb ram,Nvidia GeforceRTX 2080 TI, I-9