Daniel from Wikitude Support has found the problem: German special characters in the texture files.
Thank you Daniel!
It seems that with iOS 10.3 something was changed in the iOS file system.
Unfortunately the german version of Cinema 4D appends the Word "Oberflächenfarbe" to the texture file names when baking textures. So i had to rename every texture to eliminate the "ä" to make Wikitude on iOS 10.3.x render correctly.
The Wikitude SDK (JS API) always forces OpenGL ES 2 rendering. Only our Native API SDK allows Metal rendering.
After a quick look at the calendar I would say we can schedule your support ticket for next week.
could it be a iOS Metal issue? Is it possible to force OpenGL rendering?
Target Image is attached. You need Internet Connection fot this Target.
Do you see any warnings in the Wikitude 3D Encoder when opening the .wt3 or .fbx? This usually happens if one of the model textures is missing. Such a missing texture generates a warning in the 3D Encoder.