Pro Sites - Only creates site for highest level.

Hello

I have 3 plans (levels) which can be signed up for.

I've tested all 3. Only the highest level (level 3) successfully works fine and creates a site. The others just got to the "Finalizing your site..." page but just show the "Admin URL" for the main site not their custom site URL (and doesn't create a subsite).

Any ideas why?

Support access enabled.