I have problems getting caching to work because all my cache control header look like this.

Cache-Control:max-age=0, must-revalidate, private

While researching the problem if found this issue on the symfony project.

https://github.com/symfony/symfony/issues/25736

I just wanted to ask if this has already been reported or if this could even be my problem.

EDIT:
just found this referenced issue which states the "bug" was fixed for 3.4.3+
https://github.com/symfony/symfony/issues/26237

I downgraded symfony to 3.4.2 an header are set correctly.

Looks like this is a bugfix which breaks ez caching behavior