Steps to reproduce the issue

I just updated my Joomla Version from 3.6.0 to 3.6.1 to 3.6.2.
I have set up user group "leichtathletik" before who's parent group is "author".
I have put this group into the user access level "special" an created a category also called "leichtathletik" so that this user group is only able to create and edit articles in this category.
Before these updates to Joomla 3.6.2 all worked fine but now (without changing anything else) users which are in the group "leichtathletik" are not able to edit their articles anymore and an error message is displayed. However they are still able to create articles under this category.

System information (as much as possible)

Database: MySQLi
Joomla 3.6.2
PHP 7 CGI

Error Message when trying to edit an article which was created a minute ago by the same test user:

Category Settings for leichtathletik

Usergroup leichtathletik as child of author:

leichtathletik in user level special:

Have there been changes in the recent updates that could affect these settings?
Can I provide more informations?

Kind regards
Georg