We're using a custom theme built on top of rwd theme and when I do changes to our theme's CSS files, everything is fine for next about a day or two, then those changes are auto-reverted to previous versions of the same CSS files. JS and (p)HTML files are NOT affected, only CSS. I did look if we have (we took over the store, not build it) a scss/sass/less auto-compiler and I can't find it, so this is not causing problems.
I am not an expert in Magento but I do know my way around it, but this issue is really mind-boggling. I also noticed that there's no similar issue to be found on Google ...
Does any of you have an idea what could be causing this restoration of old CSS files? There's not backup solution set, so this is out of the question.
We're not merging CSS and JS files, they are being served directly.
Any help would be greatly appreciated!