UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36

Steps to reproduce the problem:
1. /usr/bin/google-chrome-stable --no-sandbox --headless --disable-gpu --window-size=1280,768 "https://www.google.fr:443" --dump-dom => produce dom result to the screen: OK

2. /usr/bin/google-chrome-stable --no-sandbox --headless --disable-gpu --window-size=1280,768 "https://www.google.fr:443" --screenshot=test.png => produce screenshot into a PNG file named test.png : OK

3. /usr/bin/google-chrome-stable --no-sandbox --headless --disable-gpu --window-size=1280,768 "https://www.google.fr:443" --dump-dom --screenshot=test.png => produce ONLY dom result but no screenshot png file: KO

What is the expected behavior?
How to get the html result AND a screenshot both?

The command 1 produce the dom content to the screeen
The command 2 produce the png file of a screenshot

What went wrong?
The command 3 produce the dom content to the output but not the PNG file of the screenshot!

Did this work before? N/A 

Chrome version: 66.0.3359.139  Channel: stable
OS Version: Ubuntu 16.04.3
Flash Version: 

It seems that the two switches --screenshot AND --dump-dom are incompatible? 

The question is: How to get the html result AND a screenshot both?