From the documentation it is clear that CSS files should be excluded when inside conditional comments. However, the following conditional breaks this. I'm using this to serve only IE9+ (and other browsers) a CSS file with media queries.
Thanks for the quick response! I'm so excited that my favourite plugin (Quick Cache) can now also replace wp-minify, which I have been spending countless hours maintaining on life-support in recent years!
This has been fixed in the development copy. It will go out in a future release of Quick Cache Pro.
If you'd like to use the latest version of the HTML Compressor in the current copy of Quick Cache Pro, you can grab the dev branch for the HTML Compressor and replace: /wp-content/plugins/quick-cache-pro/submodules/htmlc with the latest copy.
cc: @raamdev (QCP lead developer) ~ This fix will make it into the next official release of the HTML Compressor. I have a couple other issues I'd like to resolve before that happens, but I just wanted to give you a heads up.