In this installation, the Essential version is 2016010203.
I tested another Moodle on the same server site with Essential version 3.0.1.14 (Build: 2016010219) (2016010219)Moodle 3.0 and the same thing happens.
To replicate the problem, just add a mew "file" activity to a course. When choosing the file, choose a PDF file and in the display options, select "Embedded".
Thanks,