I have the same problem. All other WooCommerce emails sent successfully.
If I go to the stored order and resend the ticket email under the ‘Order actions’ box, the email is sent so it doesn’t look like an STMP server issue but rather some hook problem – as the ticket emails are not sent only upon completing orders.
2. You say, “I have the same problem.” Can you clarify what you are referring to? The same problem as what, or as whom? If you are referring to another thread on the forums, can you please share a link to that specific thread? I just want to make sure I have the full context of what you’re referring to! 😀