Unable to view object in AR mode

I am using the google modelviewer to view the 3D and then further use the AR functionality to view the object in AR form , my 3D is working perfectly fine , i have multiple 3D gltf files which i am succesfully able to view both in 3D and in AR form , but some of the files are not getting viewed in AR form , it is not showing anything when i am clicking on small cubicle form which opens up the object in AR form , there are some gltf files which are around 22MB size , which is not getting rendered in AR , and some files are around 10MB but still not getting opened up in AR while it is perfectly getting viewed in 3D form .

please help with the following issue .