Failed to retrieve Avatar Specification for user id (http response code: 400)

Hi,

I know that this problem has been discussed in other posts but none of them had a solution. I'm trying to create a simple multiplayer app to test some interactions. I have the needed Rift and AppLab apps. There's a build on the alpha channel with some users added for access. When the people enter to the App, the local avatar spawns correctly, but the remote one doesn't. The errors that appear in the console are the following:

[ovrAvatar2 native] stats::url file transfer failed: http response code: 400
uri: https://graph.oculus.com/7413158262106467?fields=id,avatar_v3%7Bmodel.profile(rift_v04b).platform(pc).sdk_version(Avatar2%20runtime%20SDK%2020.3.0.17.0%20client%20SDK%2020.3.0.17.0).client_version(0.1.0%2B2022.3.4f1).client_name(<project_name>){url,id,creation_time,animation_set}%7D
error: No error
error details:
trace-id: CTJBp1WJMFP

[ovrAvatar2 native] specification::Failed to retrieve Avatar Specification for user id <user_id>

[ovrAvatar2 manager] UserHasAvatarAsync completed the request but the result was NotFound

I suppose that the last 2 errors are consequences of the first one, but I can't make it work.

The related posts that talks about this problem are the following:
https://communityforums.atmeta.com/t5/General-Development/Meta-Avatar-load-fails-with-Failed-to-retrieve-Avatar/td-p/1029689
https://communityforums.atmeta.com/t5/Unity-VR-Development/UserHasAvatarAsync-completed-the-request-but-the-result-was/td-p/1111501