I’m sorry, but thats not about me. Thats about 3DSMax/Assimp. File formats can be very complex and FBX has multiple versions as well as ASCII and BINARY. FBX provider Autodesk does not even publish the specs of the file format, only the SDK that everyone should make use of. Though, new versions require the ThirdParty tools to upgrade their SDK version. Some ThirdParty applications try to write their own FBX importer/exporter, without using the SDK (Assimp does that).
As alternative you can try GLTF as that is very common now as well.