You probably refer to the old KAS functionality (more than a year old, to be specific). In the today's KAS all "struts" are specific parts. Like TJ-1 and JT-2. They all connect to JS-1 port. You cannot connect two JS-1 ports together unless you've enabled the legacy mode (read MM-LegacyKASPipesPart.txt in Patches folder). Which part are you using for docking? Could you please record a short video?