Hi,
If you see the email in the email history, then HikaShop sent it to the email server of your hosting.
And if other emails are received, then the connection with the email server and thus it means that your hosting email server processed the email.
And if you don't receive the email in that case, then your hosting email server couldn't transfer the email to the receiver email server for some reason. It's possible the email was flagged as spam, but it's also possible that it's a configuration issue.
For example, if the "from" and "to" of an email are the same, it's possible some email servers discard the email.
However, the only way to know the reason is to read the log of the email server for that email, and only your hosting provider can do that (if you're using the email server of your hosting provider to send emails, of course, but it should be the case most of the times).
So in that case, the best is to do a screenshot of all the information of the email in the email history and contact your hosting company support and ask them why that email was not received. With the information of the email from the history, they can look into the log to find the reason and tell you what's wrong.