When converting a COLLADA model to glTF/glb using the online converter I have problems with the transparency of polygons when viewed from the backside. Polygons that appear (correctly) transparent form the backside in the COLLADA model become opaque once converted.
Attached are simple example files for an original COLLADA model and the converted model.
rmax_rotor.glb (305 KB)
rmax_rotor.dae (9.48 KB)