I've noticed a few attachments with 0 views although people have clearly viewed them. I opened them myself and kept an eye on the attachment table in the database, views for that post never increased from 0. The table xf_attachment_view is empty, not sure what it should contain. Running the update views cron never helped either. I've only ever updated versions as far as major changes go and added a few mods, so I have no idea what could have gone wrong. Any suggestions appreciated.