Post-Slug gets added twice, if page is a top-level page itself

Hi Sami,
I’ve installed this plugin to use a link structure like this on my custom post type:

domain.cno/<post-slug>/ (instead of domain.cno/<post-type>/<post-slug>/)

I want to use a hierarchical structure, for example:
domain.cno/<post-slug>/<child-slug>/

So I set this rule in the PostTypes Permalink Settings:

%parent_postname%/%postname%/

But now it happens, that all new pages, that are on the top-level and have no parent page itself, get a permalink like
domain.cno/<post-slug>/<post-slug>/

It seems it uses the %postname% also as %parent_postname%, instead of leaving the parent_postname empty, when it doesn’t exist.

At the moment, I can save the correct permalink only after I tried for a second time. On the first save action, the wrong permalink gets created, after that I’m able to modify if to the correct one and save again.

Can you reproduce this issue? Thanks a lot!