On switchboards, it's quite common to feed not only transformers and other panels but also large loads such as an RTU.  Currently, by setting the number of one-pole breakers parameter in a switchboard, it sizes the panel schedule correctly.  For example, if I enter 16 into the max # of one-pole breakers, the panel schedule shows 16 circuits.  However, I cannot circuit 16 3-phase loads.  This is a serious problem because I would like to feed the disconnects for my larger equipment (an X-ray, an MRI, some pumps, etc.), along with some other panels, from a switchboard.  I have two panels circuited to the switchboard, and I would like to circuit six or seven more 3-phase loads along with a couple of 1-phase loads.  On a switchboard, this should only take up 10 or 11 slots, so 16 should have room for spares.  However, I can only circuit five 3-phase loads before I'm told the panel is full.  The panel schedule shows 11 empty slots, but I cannot choose the panel when I'm circuiting my loads.  If I increase the number of breakers to 18, I can fit six loads now.  If I increase to 21, 7 loads.  The loads only take up one slot (as they should), but in some calculation happening on the backend, Revit thinks the panel is full when it is 1/3 full.