As Gizmo wrote,
it looks like in your Moderator forum, you are denying "Can see forum" permissions to guests, while giving them "Can read threads" permission.

Attached screenshot of the correct setting for your desired configuration.

It's probably also a good idea to review the rest of the your [admin/moderator forum title] Forum Permissions while on its page.
Attachments
20181125_22-18-01.PNG


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