Plugin Oauth error: "Error getting system message: {"message": "User is missing credentials"}"

GPT builders Plugins / Actions builders
14

For what its worth, I am trying to get google as oauth provider to work with my plugin, and experience the same behaviour as OP: after plugin install everything works for a few hours. In the plugin code, I am able to query https://www.googleapis.com/oauth2/v3/userinfo with the bearer token passed by ChatGPT (so this is a correct access_token retrieved by ChatGPT on google’s authorization url)
Then at some point in the ChatGPT UI: 'User is missing credentials". This without a hit on the plugin api itself.
Auth part of my ai-plugin.json

    "auth": {
        "type": "oauth",
        "client_url": "https://accounts.google.com/o/oauth2/v2/auth",
        "authorization_url": "https://oauth2.googleapis.com/token",
        "scope": "profile email",
        "authorization_content_type":"application/x-www-form-urlencoded",
        "verification_tokens": {
            "openai": "khaskfhsklfhd"
        }
    },

the client_url and authorization_url match the ones advertized by google on https://accounts.google.com/.well-known/openid-configuration

There is not much else able to configure here. The same Oauth client config on google works fine (even after much time passed) when used with e.g. the nextauth.js demo application (https://github.com/nextauthjs/next-auth-example), so I am guessing the oauth client settings I created at google should be ok.

If anybody has any ideas left to try, would highly appreciate it!