In such a case, could you please set it to “PHP “mail()” function” and see if it’s work. But if the issue persists then I would suggest you install a plugin like Email Log on your site so you can see what the status of all the emails sent is.
If they are being sent, most probably they are going to SPAM, and sometimes they can’t even get to the SPAM inbox. In that case, you just need to improve the deliverability rate of your emails.
In order to do that, you can try to use an SMTP plugin like WP Mail SMTP by WPForms, for example.
If even after that you still have problems, you can try to configure DKIM or SPF records. You may need to contact your hosting provider to understand how the setup will work.