reply will appear after moderator approval

Hi James, this depends on your community settings. Does your community have pre-moderation turned on? You can check this in Admin > Mod Tools > Moderation > Forum Moderation. 

Another possibility is that some posts are just getting pulled into the Spam Quarantine. The Spam Q can be found in the Community Dashboard, and should be checked frequently. 

Hello James_Avery , If a new user posts something, the moderator will review their posts. Genuine users will be assigned the 'Pre-mod bypass' role, allowing their future posts to be published directly in the community.