No, it won't be accessible. The difficulty is really that ideally we need to see this happening so we can confirm the situation, as it's certainly possible there's something on the server potentially blocking the request.
In one of the examples you've shown that don't work, are there any attachments? Can you show us the raw BB code of the first post/article? (You can use the "[ ]" toggle to turn to that display. Probably worth sticking the contents into a text file and then attaching it so it doesn't get parsed here.)