Blog Categories in menu have different blog-styles

Hi,
my customer has Enfold for her website. Since upgrade the blog works difference.
Here website ist http://www.entfaltungsparadies.com und her blog can found under “Entfaltungsblog”.
The submenus of “Entfaltungsblog” are blog-categories.

If I click on “Entfaltungsblog” or “Entfaltungsblog -> Coaching” I get the correct representation –
a list of blogarticles. This representation is selected in the theme options -> blog.
At the end of the article I fínd the pagination.

If I select “Entfaltungsblog -> Familie” i get an other representation – one article of the selected category.
And the Pagination from one to the next or previous article I get on the left or right side.

I found out, that there exists a page “Coaching” with url entfaltungsparadies.at/coaching. This is the reason, why the
blog-archive-page for “coaching” is shown in the correct form.
Now I created a page named “Familie”. Now the Blog-Page for “Familie” is shown in the correct representation, the same
with “Zitat”, “Wöchentlich Gelassenheit” and “KISSS”.
Only Podcast was not shown in the correct reprasentation because the permalink of the page ended with -2 and the page
was shown empty.

Now I began to test, what the change of category will influence.

The link in the dropdown-menu was shown as entfaltungsparadies.at/blog/coaching – visible at the bottom left corner of the browser-window. When I loaded the page, the link of the blog-archive of coaching was shown without /blog/ in the middle in the address-line of the browser!!!

Now I changed the category-base to blog. The result is, the “blog” in the permalink disappeared!!! (again visible in the bottom left corner of the browser window) and the podcast-category-page is now shown in the correct representation.

Why I have to create pages for the blog-archive, so that they are shown correct?
Is this new?

Best regards, Daniela