Configure OIDC connection for Single-Page-Application

I added an OIDC connection for an SPA (react). The configuration was given to me by the institution we’re setting the connection up for. When using the OIDC connection to login, I receive this error:

Failed Login:

invalid_client (Client authentication failed (e.g., unknown client, no client authentication included, or unsupported authentication method) The OAuth 2.0 Client supports client authentication method “none”, but method “client_secret_post” was requested. You must configure the OAuth 2.0 client’s “token_endpoint_auth_method” value to accept “client_secret_post”.)

I have updated our oauth client to use “client_secret_post” as the token endpoint auth method but I still receive this error. Any help would be greatly appreciated!