Hi! I've managed to get the access token, using the scopes: read write chat, but I can't start agent session. I get "UNAUTHORIZED" error every time:

{\"errors\":[{\"UUID\":\"ccd32285-5895-45c4-bec5-6bd27b15f4a2\",\"message\":\"<html>\\r\\n<head><title>500 Internal Server Error</title></head>\\r\\n<body>\\r\\n<center><h1>500 Internal Server Error</h1></center>\\r\\n<hr><center>nginx</center>\\r\\n</body>\\r\\n</html>\\r\\n\",\"name\":\"UNAUTHORIZED\"}],\"data\":null}",

Can you help me, what am I missing?