Invalid OAuth in game - works when testing in Postman

This is what I get in Postman:

{
“data”: [
{
“id”: “83277609”,
“login”: “ibzy_”,
“display_name”: “Ibzy_”,
“type”: “”,
“broadcaster_type”: “affiliate”,
“description”: “Returning after a long hiatus, getting back into the swing of things with Splitgate, Phantom Abyss, and interactive classic DOOM streams. Enquiries: Lee@ibzy.co.uk”,
“profile_image_url”: “https://static-cdn.jtvnw.net/jtv_user_pictures/6ea7e9a4-6694-470d-b412-e06ccc2c2ee1-profile_image-300x300.png”,
“offline_image_url”: “https://static-cdn.jtvnw.net/jtv_user_pictures/4af69a58-50e1-45ff-ad3d-0111adc05ff4-channel_offline_image-1920x1080.png”,
“view_count”: 69522,
“created_at”: “2015-02-20T23:21:04Z”
}
]
}

And this is in my debug.log:

{“error”:“Unauthorized”,“status”:401,“message”:“Invalid OAuth token”}