The editor gets forwarded to the dashboard if accessing the second menu in the drop-down list.
This issue has the same reason as the problem you described at 08.10.2016. It was described here.
I registered ‘action’ and ‘menu’ parameters for the nav-menus.php at development version 4.29. Beta 5 will be available for testing this week. I will just finish some tests with it myself.
Yes, unfortunately I reintroduced this bug after refactoring “Admin menu access” add-on code this year. It’s necessary to apparently register URL arguments for WordPress commands which used/blocked with “not selected” model – I missed some such arguments. So thanks again for your help.