I've recorded a seminar with three cameras. One of them is a GoPro Hero 4 Black. I used Protune in the GoPro and then converted the files to AVI in GoPro Studio, which I guess turns them into Cineform AVI's, at least their size about doubled.
I then added them to the Vegas Pro 14 timeline but when doing so Vegas crashes and shows this message:

The error reporting dialogue says:

I happens both if I add the media straight to the timeline and also if I import the media first and then add to the timeline. The crash happens after pressing Try again a few times. If I press Ignore the clips seem to get to the timeline but most of them without video and/or audio.
So, what's wrong here?
Cheers Martin