There is an issue with mesh uploads in .glb (or .gltf) format. It seems that SL applies all rotation values to the uploaded mesh, which is not good, as this did not happen with the Collada (.dae) format. When uploading rotated objects, the rotation values of all rotated objects becomes 0,0,0, while the mesh model stays rotated visually. This results in shifted axes on the uploaded mesh, which among other things, makes in-world scaling distorted. In other words, the object's bounding box don't align properly with the mesh itself.