All my sandbox token requests getting a 401 "Entitlements have not been set for this Account"

All my token requests in the sandbox environment all result in a 401 "Entitlements have not been set for this Account", e.g:

Token.mbs_token_callback(
{"status": 401,
"results": {
"type": "FDToken",
"status": "failed",
"error": {"messages": [{"code": "401", "description":"Entitlements have not been set for this Account."}]}
}})

As far as I know, this was working Friday. Is there something wrong with my account or the sandbox?