Image Styles not generated on production server

Hi all,

I’m having problems with getting image styles generated.
Even the default thumbnail in admin section doesn’t work.

What does work however is the sample.png file in admin image styles, those are generated and the folders are created also. So not a permission or user issue I guess…

Locally everything works as it should.

Drupal 8.1.8
Server OS: Debian
User Permissions: www-data and even tried 775 and 777 without any luck
Status report says all is good:
File system Writable (public download method)
GD library bundled (2.1.0 compatible)
GD library PNG support bundled (2.1.0 compatible)
PHP 7.0.11-1~dotdeb+8.1

Any ideas?

Thank you in advance!

Drupal version: