How to refresh minified CSS with Hummingbird

Hi,

I have made some changes to my style.css file https://www.pcsteps.gr/wp-content/themes/magazine-pro/style.css but they haven't propagated to the minified css file Hummingbird creates.

What can I do for the changes to propagate?

I tried removing style.css from minify, but it didn't do the trick. Is there a flush cache option that I am missing?

Thanks