I was on the same boat, I also checked the "Do Not Include Guest Receipt Contents" and now I no longer see the account info being displayed on the registration receipt page which is great.
I added the mobile # field on the login page and made it a mandatory field, the client gets an SMS with the account info BUT I'm no longer seeing the "Login" button on the receipt page. clients are now "stuck" on the receipt page.
I looked on the guest_register_receipt and notice the submit field is now set to "null". I created a new submit filed but can't add it to the guest_register_receipt form.
Any idea?
Thanks