The 0 of this option doesn't disable Spam control, if you read this topic properly you should know the Spam Control should be turned off for this purpose. Please try to set "No" the spam control. And make sure you use the latest version. Also you can decrease the spam suspect ion level on the same admin page, it's described here:

https://wpforo.com/community/how-to-and-troubleshooting-2/how-to-turn-off-the-1st-post-topic-moderation-requirement/#post-8222