Pro Site signup creates site immediately when the free signup is Disabled

In Pro Sites the Allow Free Signup is disable. The new site is created as soon as the registration is completed. Initially the there was only one level with 0 set as price and no payment method set.
Set price other than 0 but still the site is created at the time of setup. All other plugins except WPMUDEV Dashboard and Pro Sites is disabled and the default WordPress theme is activated.