Cant edit CSS STYLE properties (grayed out & blocked) in chrome

Question

I am experiencing (havent seen before) something strange issue. When I enter a site (site in question is RunForGithub.com) first time, and open up Chrome Inpsect console, then I can modify the css properties on the fly. However, when I refresh page (F5) i can no longer modify them:

the properties area is grayed out. BUt, this only happens with specific only one loaded (runforgithub.com/_styles.css) file, and not with other .css files. It's very annoying, any ideas?

Answer 1

Closing the dev tools and opening it again fixes this temporarily. Here's the official bug report: https://bugs.chromium.org/p/chromium/issues/detail?id=796629

Answer 2

This was approved as a bug and will be fixed in near future:

https://bugs.chromium.org/p/chromium/issues/detail?id=796629