I’m sorry.
But I tried a few extra downloaded objects. I converted them by hand using Blender and i tried to convert them online.
In the webviewer you supported in your reply they work fine, In MindAR they work fine, but i still get a bug in my viewer on android. (tried 4 different objects, even with different source object types. And coonverted them to GLB and GLFT)
Thank you for your suggestions so far.
Do you have additional ideas?
And could you please test the url to see if you get the same feedback in the Android Chrome browser