Attempting to tag fabrication connectors results in a "Specified argument was out of the range of valid values." error

Hello! The issue is essentially what is stated in the title. When tagging elements based on the family name, the fabrication fittings (not the straight duct) cause the tag.byelement to throw the error “Specified argument was out of the range of valid values.” Any help would be greatly appreciated. I have attached a screenshot of the program for reference.