Another user (admin) made a post with an embedded image (attachment). When I (also an admin) load it I can view the text, but I get a broken image. Inspecting the element shows a 403 error. She says it shows up fine for her. How can I debug further? Possibly relevant: she also has a problem sometimes where she invites several people to a conversation - one of them gets the invitation, but he gets a permission denied error when trying to view the conversation. I've just upgraded from 1.4.3 to 1.5.5 and the image is still broken.