Well, if that’s true, honestly I have no idea because the auto post is added AFTER the topic is created. It can’t be before because a reply needs an item (topic in this case) to exist. In 6 years of the existence of this plugin (it comes from IP.Board 3.3), that’s the very first time I hear this.
Anyway, “sometimes” is too vague to try to fix something virtually impossible to reproduce, due to the way it is build. So if you have more details to provide, I’ll be happy to take a look.