Facebook (Instagram) Graph API not returning instagram_business_account

First of all, let me explain what I have today:

• I have a access token with the following permissions: email, public_profile, pages_show_list, pages_read_engagement, instagram_basic, instagram_manage_insights
• I have a valid access token
• The accounts that I'm trying to access are Business Account or Content Creator account

With that in mind, here's my problem: some users that are connected to my platform simply don't return the instagram_business_account when I'm requesting /me/accounts.

My request is to https://graph.facebook.com/v10.0/me/accounts with the fields id,name,instagram_business_account{id,biography,ig_id,followers_count,follows_count,media_count,name,profile_picture_url,username,website}.

Here's a sample result where both should return the instagram_business_account, because both are connected to Facebook as a Business Account:

{
    "data": [
        {
            "id": "xxxx",
            "name": "xxxxx"
        },
        {
            "id": "xxxxx",
            "name": "xxxx",
            "instagram_business_account": {
                "id": "xxxx",
                "biography": "xxxx",
                "ig_id": 00000,
                "followers_count": 0000,
                "follows_count": 0000,
                "media_count": 0000,
                "name": "xxx",
                "profile_picture_url": "xxxx",
                "username": "xxxx"
            }
        }
    ],
    "paging": {
        "cursors": {
            "before": "xxxx",
            "after": "xxxx"
        }
    }
}

Does anybody have any idea what is the problem happening here?