I did test here, the way that worked for me.
Create a project for each file.
Open File / Batch Produce ...
Add Project 1
Choose the profile, HD 720P
Add remaining projects
But is not practical, but can be useful if it will take a long time to render, you can do something else.
AMD-FX 8350 / 8GB DDR3
SSD SUV400S37240G / 2-HD WD 1TB
AMD Radeon R9 270 / AOC M2470SWD
Windows 7-64 / PD16 Ultimate