I added a block for comments where I want my students to post, but not read. It's just a method of messaging me if they need to request a document. I limited permissions on reading comments to just teachers and managers (removing authenticated users, guests, and students). They can still see their comments and other user comments.
The permissions I revoked were under Front Page permissions and I filtered by comments. To ensure I was revoking the correct one, I revoked "post comments" (located right above "read comments") to authenticated users, guests, and students, and the ability to post was removed. So it is the correct category (Capability Course). Is this a bug or a misunderstanding on my end?