All current Shapr3d versions on Apple devices do not export USDZ properly to support materials when viewed at least on Apple platforms. Simple previews may work but it’s likely bc shaprs export and those viewers are both using outdated and incorrect USDZ structure.
To reproduce, create a shapr project with one or more surfaces with a material. Export it as USDZ. View it in the preview app on a Mac with MacOS 27+ or an Apple Vision Pro on 27+. The materials do not display. The materials are present in the file but the texture to material associations are not there. Remapping is nearly impossible due to the way the textures are named and/or generated.
Please bring the USDZ export to the current standards.
For those who need a workaround, you can export GLB files, open them in the preview app on a Mac, and export to USDZ. That process maps the textures properly but there is at least one issue : default materials with transparency from shapr3d display as opaque. You have to use thick glass as a workaround. I don’t know if there is a loss in quality going through these conversions but at least it will allow you to see the materials again. In my case this was critical on the AVP… probably the main reason that I chose the shapr > usdz > AVP workflow in the first place.