@glnhrrs Can you provide the tileset (if it’s not too large), or the specific B3DM that it mentions, so that others can have a look at what might be wrong with that file?
Here is a single b3dm Is this enough to work out issue?
Yes, the single B3DM is enough in this case.
This doesn’t mean that I didn’t spend waaay to much time figuring out what is wrong there, but this is mainly due to the somewhat obscure error message, and code that I’m not so familiar with.
The parsing error was caused by the fact that the B3DM contains GLB data where the JSON contains "mimeType":"image/webp". It should probably not cause a parsing error, and this issue is now tracked at Unknown image MIME type in glTF causes unspecified parse error · Issue #258 · CesiumGS/cesium-native · GitHub
But note that even if this issue is resolved, it will not be possible to load the asset, because the WEBP image format is currently not supported (and of course, in the future, this should just print a message like “Webp is not supported” instead…).
I saw that the asset was generated with RealityCapture - maybe there is an option to change the image type from WEBP to PNG or JPG?
Legend ! Half of that made sense 
I will work this out in RC and see what options I can get.
Thanks again for your help mate.
No options to change the actual format of the texture on export. Or during processing the mesh. I will see if I can pass this one to the RC team.
Cheers
Talekd to RC support.
Current relase doesnt support this web format jpg export. This should be updated shortly