TYPO3 Core

Here is another screenshot from the same website.

As you can see there are only two sites on root level (red and purple in the right part of the screenshot). But in the page tree the red (old) page appears twice.

So there must be a difference in the select statement of the "Seite" section on the right side of the screen and the selection for the pagetree. (different number of params during select???)

False picture added :(

Here is the correct one.

Please check the database mounts of the user.

Actually the user is an administrator user.

And there are no db-mounts selected. (twin_tree3_dbmounts.png)

This can happen if admin user is member of a group, has "mount from groups" enabled (which is default and unfortunatly only to be seen, when you disable admin) and the group has a mount.