I've had this issue with my Magento 2.2.3 installation where nothing gets updated in the pub folder. So every time I re-deploy, product images don't get re-populated, and no CSS changes will go through. I've only been able to add rules by putting CSS in template files, those update just fine. I'm not sure what happened to it, it was working fine at one point.
I've tried several CLI commands including static-content:deploy of course. It sounds like it could be a folder permission issue, but when I look the pub folder has the same permissions as the app folder. Anyone else run into this issue?