Sporadic issue wp-discourse/SSO: Nonce has already expired

I used a similar method in several projects with lastest version of Wordpress and Discourse. I used Wordpress as SSO provider. It works correctly.

Are you using the standard Wordpress registration system? Custom functions on function.php can cause conflicts but it seems that your problem is not related to it. Also, you can check API and Webhooks.

After solving this problem you will probably need to be that: