I removed QGC, rebooted, and reinstalled from your link and rebooted. The link is to firmware ver. 3.5.1 and git ver. 28fdbf65. - same issues.
This sounds like it is not a problem with the new version, but an issue with the installation or registry. I’m not well versed with how to fix these sort of things with Windows, so I will have to find out from the other developers how to troubleshoot this and follow up with you.
Only now in safe mode, if I have the camera gimbal on input ch8 and the output on 8, and select camera down on the controller, the mount will motor fully down and then back to its original position. After that no camera movement.
Ok, this sounds like it might be a bug in ArduSub firmware. I would like to sort out QGC first, and then address this.
Possibly roll back to an even earlier version of QGC?
I advise against this at the moment, older versions of QGC will be incompatible with newer versions of ArduSub firmware.
I am sorry you are having trouble with this @Teggles. I will do some homework and follow up with you as soon as I can.