I created a post group "logged-in users only", but I cannot select the page "hidden link" to add to this group. When I start to type "mein...", the form does not respond. It tells me "no results found".
Your hint gave me the clue: On the edit page of the "my account" page, yes, there is a Post Group meta box.
But it told me that the content type "page" was not managed by the Access plugin. (see screenshot)
As I only followed the instructions above mentioned, I went straight to the "post groups" section in the Access plugin and unfortunately did not pay attention to the other settings of the Access plugin. Now I changed the access management to include "pages", and I can select pages... Surprise! 😉
(Means that I will have a deeper look at all of the other settings, too.)
Thanks for your help, this topic is closed for me.