This is a side effect of a feature we recently added. To get around the issue, you'll need to do the following:
- Go to the forms page and click on the Login tab.
- Scroll to the bottom of the page and click "Build a custom login form."
- Click "Test login page" at the top of the page.
- Enter your login page URL or the word "login" if you're using the default Memberstack signup modals.
- Scroll back to the bottom of the page and select either "Pop-up modal" or "Build a custom login form."