For the PC message to work it has to be sent early to an elektron device. They’re designed to both send and receive PC during the last step of the preceding pattern. That’s what you need to do on the non-elektron device.
EDIT: If you ARE sending the PC early and it’s still changing one bar late then you may be hitting the known problem with some settings on the receiving elektron box. If you are NOT sending early it won’t work.