The wavy marks seem to appear for me whenever the scanned surface is approaching a perpendicular orientation relative to the front face of the scanner. I am guessing this is caused by the projected light patterns being stretched into thin bars along the surface as it sharply angles away from the fronts of the cameras. It seems to happen with vertically oriented surfaces more than horizontal ones.

You can avoid it by ensuring you keep this type of view to a minimum when scanning, or by reorienting the object so that the sharply angled-away surfaces are scanned horizontally.