Some people can't see mental images

I wouldn’t doubt that maybe there’s also some condition where people can’t see physical images at all. Like they know where stuff is because signals go to their brain but if you ask them to describe what they are seeing they can’t, they see nothing. It’s really not much more bizarre than aphantasia.

There are several levels of this. There are people who can do things as though they see but have no conscious access to the interpreted visual information. Or they can do something that requires vision with one hand but not the other.

You can think of it like a bunch of different subsystems responsible for different kinds of tasks and some of them can be broken so the connections between them don't work.

Read Hallucinations by Oliver Sacks for a lot of case studies.