Go to your admin panel > modules tab > edit the forum module > edit a specific forum you believe this is occurring in
- Look specifically at the following 2 permissions "Only view thread list" & "View access"
- "Only view thread list" means that the users can only view the list of threads in the forum, but can't actually view the content within the thread. Unless you truly want this, you should remove all tags listed here
- Make sure the user has the correct access under "View access" for this forum area
- Still can't find the issue? Double check all other forum areas
- Still can't find the issue? Make sure nothing is set under "minimum posts to view"
If you're still having issues after checking all of this, use the support form in this help center.