Steps to reproduce the issue

• Create New Menu Item
• Select any menu type
• Set the alias to a word, such as "mediation" (you can do anything that begins with media)

Expected result

• Loading /mediation on the front end of the website would load the correct menu item.

Actual result

• 403 error is thrown on the front end when trying to load /mediation.

System information (as much as possible)

• PHP 7.1.10
• Joomla 3.8.1
• Database Version 5.7.19
• Web Server nginx/1.10.3

Additional comments

• It does seem to load properly when setting a Parent item on the menu item.
• If you put something in front of media, for example test-media, it does load properly.