I think we now know what the problem is. It seem like some mistake in the transcoding and maybe in the camera options. I have a guy looking at it at the moment and will return hopefully with a full explanation.
Btw thanks for the help Peter Moretti. Always nice with someone trying to help
EDIT: it seems like the problem is in Red Cine-X. In the export settings you have to remember to click the "Sub-folder per clip" ON, otherwise you won't get any AAF which means the whole import process doesn't work.
I think it's something you should at least get warned about in future RCX releases.
Hopefully this will help some people in the same situation.