If you are updating to ACSS 3, set your colors, and then find that the colors are not showing up in the Bricks color selector, all you need to do is deactivate and reactivate ACSS. This will repopulate the color folders.

Also, if you use the ACSS Purger plugin, you will need to refresh the purged CSS to make sure new styles are available. Personally, I found this too cumbersome and deleted the plugin.