Typically, users are unable to attach an email to NetSuite because the role they are signing in with does not have the appropriate permissions for the specific record type, the roles do not have web services permissions, or the email is still being processed by NetSuite.
If all your prerequisites have been met and there are no error messages, then there may be a delay in NetSuite processing your email. Emails typically show in NetSuite in less than a minute but if your NetSuite account is busy, it could take longer. Learn how to check the status of your sync in NetSuite here.
If you're still having trouble, contact us using the chat icon at the bottom right or send an email to email@example.com. Please provide as much detail as possible. Screenshots are welcome!