Sadly it does not work with flex elements :-(
Thomas Parisot

Could you provide me with an example? In which browser do you have issues with page-break-inside and Flexbox?

I made a real quick test in Chrome Canary on macOS Sierra and everything works perfectly fine. ( /

One clap, two clap, three clap, forty?

By clapping more or less, you can signal to us which stories really stand out.