Hello,
with the current version of the SDK, multiplatform uploads are more difficult and confusing.
It may work just fine if you have the exact same avatar on each platform, but this is rarely the case.
Usually there is one scene for each version of the avatar, because of the different features each platform allows.
In the previous version, there was just one dropdown to select the target platform. Now a platform needs to be the only selected one.
Suggestion:
Let us define (a dropdown, for example) in the avatar descriptor what the target platform is.
In this way, we are able to just place all avatars in one scene.
This may be can be extended, to allow setting a path to a scene containing the avatar for a platform.