Activation link sent by Ghost to a new paying member redirects user to the signup page?

Had no issue’s ‘onboarding’ my first 19 paying members, now I get a new paying member emailing me he’s being sent into a loop…which is normal because the link he got is a signup link and not the ‘signin link’ that I guess he should have gotten.

Screenshot of the page he gets sent to…

I didn’t do any changes to my default.hbs or any other changes since accepting paying members. The theme is based on Lyra and no changes were ever made to the default.hbs file.

There is also no real way to test this, will it happen with every new paying member now or not?

But most importantly, how come it happened now and not before? (again, no changes were made to the theme since launch)

What should my next steps be?