Empty answer from Nadeo services

[ElRubioLoco]

Whenever I send following request :

POST live-services.trackmania.nadeo.live/api/token/leaderboard/group/map?scores[7hk8IflYsbMbpJv2gyYzx48Zvt7]=sys.maxsize

With the following body :

{
    "maps": [
        {
            "mapUid": "7hk8IflYsbMbpJv2gyYzx48Zvt7",
            "groupUid": "Personal_Best"
         }
    ]
}

I get an empty request, like an empty byte string (b'')

My headers are :

{
        "Content-Type": "application/json",
        "refreshToken": "*Refresh token*",
        "accessToken": "*Access token gotten when we authenticate*",
        "User-Agent": "How many contenders / howmanycontenders@gmail.com",
        "Ubi-AppId": "86263886-327a-4328-ac69-527f0d20a237" /* The one gave in documentation */
}

I authenticate by :

1. Sending a POST request to public-ubiservices.ubi.com/v3/profiles/sessions to get a ticket.
2. Sending a POST request to prod.trackmania.core.nadeo.online/v2/authentication/token/ubiservices with NadeoLiveServices audience in it's body and ubi_v1 t={ticket} in my authorization header.
3. Storing the tokens received and sending them in my headers whenever I make a new request.

I certainly didn't understand some authentication things and that's why I get this empty response but I can't figure it out.
Note that the authentication works though.