Are you using the Ticket for backend access that’s shown in the Sharing and embedding tab of your dashboard? If so, please let me know which model is giving trouble, either here or in a private message.
Ok, please use the backend ticket shown on your models’ dashboard (the one starting with 0a2da6c659...), not the one that was provided to you previously for testing.
I justed tried using postman and the backend ticket shown for your model on your dashboard and it worked.
What kind of client are you using to make the requests?