After having a similar issue a few times, I found out the cause (at least in my case)
I swap memory sticks between my Sony camera and my GoPro Hero 6. If I swap memory sticks and connect the camera to the harness BEFORE turning on the GoPro, it doesn't seem to recognize the memory stick and the Karma gives me a camera error.
Not sure if this is a fix for you, but I have seemed to notice this pattern.