I am using a Ronin S with a Sony 6400 camera. I have been trying for too long and I still get the same message on the view finder. Check the connection is the message. I have upgraded the Ronin firmware, tried a couple different cables and still nothing. I am have had this setup for almost a year and I have barely used it. I need the record function on the Ronin to work with the A6400. Very frustrating.
Any help would be greatly appreciated.

Hi there, I am sorry for the difficulties you encountered. Start/stop recording video is supported while using the MCC-Multi (optional), MCC-B (in the box), RSS-IR (in the box) for Sony A6400. Please note the connection method should be as instructed on the website https://www.dji.com/support/compatibility/ronin-s/a6400, e.g. method of connecting the gimbal and camera via MCC-B cable. If the issue persists, please provide a video of the issue for better confirmation, thank you.