Change WordPress user roles and capabilities › Forums › Restrict or Permit access inside WordPress – how to › Manage option restriction issue withe latest upgrade › Reply To: Manage option restriction issue withe latest upgrade
Empty page can be a sequence of PHP fatal error.
Can you look at PHP errors log file at the server where you have a problem?
May be activate temporally WordPress debug mode: https://codex.wordpress.org/Debugging_in_WordPress
It will show a source of a problem in case a PHP fatal error takes place.