I created this script, but it only works if I select elements of same configuration. e.g., only CQUAD4 elements or only CTRIA3 elements, If I select a combination of both, it doesn't work.
def MCID_set(mc_ID):
elements_collection = hm.CollectionByInteractiveSelection(model, ent.Element)
MCID = ent.System(model, mc_ID)
elements_collection.set_values('MCID', MCID)
print('Done')
MCID_set(System_axisID)