ctml turns out the discussion that replies were posted on had no first_post_id set in the database. I think this may have been caused by the original issue fixed in 1.0.4, originally when the discussions were posted using the older version of webhooks the webhook failed due to the bug with follow-tags and during discussion creation the first_post_id wouldn't be set for those discussions. For any replies on the thread after webhook actions would be ignored, after I set the first_post_id manually for the handful of discussions webhooks began working. I guess the first_post_id doesn't get set because of an issue related to error handling in flarum core, the first_post_id should always be set if the discussion is created and first post is posted regardless of other failures that may occur (such as emails, webhooks, or anything else that may run during the discussion creation process)
Anyways, I hopefully should be all good now 🙂
