I have pattern containing 32 identical solids.
I create a 'boss' in the middle and then combine them. Or, at least attempt to...
IIt elects to join the boss to every other spar; and any attempt to combine the other 16 collectively or individually is met with the ever annoying "Unable to intersect bodies".
If I duplicate the boss, I can the combine it with the other 16 spars; so there is nothing wrong with the spars.
Of course, attempting to merge the two sets of spars+boss togther fails!
If it wasn't so frustrating, it would be laughable.