On every browser on every device: Apparently at random, the tabs just vanish for some of my open emails. I've even seen it happen while I'm looking right at it. Once the tab is gone, if I navigate away from that email, there's no way to get back to it, or, if I'm already somewhere else in the inbox, the email just vanishes. I've reported this multiple times. You told me to send a message about it through Twitter, which I did, never got a response, and this has not been fixed.