Thanks again for the bug report. We've managed to get someone on the team to reproduce the issue, it seems login-by-email doesn't work correctly in Safari for iOS. We found that after you click the email login link, it'll appear you're logged out, but once you refresh the page, you'll be logged in.

We'll work on getting this squared away, but in the mean time, perhaps try the refresh- workaround; or a different browser or OAuth login method.