User emails not sending

I’m having a lot of difficulty getting the new user emails to send to the registered email address. I have worked through this guide https://www.paidmembershipspro.com/troubleshooting-email-issues-sending-sent-spam-delivery-delays/ to no avail having tested with SMTP plugins and without.

When a new user signs up the admin gets an email with all their details but the user gets nothing to their email unless I check the “Default WP notification email” box on the Email settings page. I don’t want to use this though as it doesn’t send the new user the relevant information.

Wordpress seems to be sending emails fine (tested with password reset) so I’m at a bit of a loss now. I’ve tried changing the “From Email” in the email settings too to emails from my domain, gmail ones and simply leaving it blank but it’s still not working. Any help would be much appreciated.

Just to note I am currently testing before launch by using 100% off coupons to test the sign-up process, I presume this shouldn’t have an effect but is worth mentioning.