I've noticed my hash rates recently dropped (AMD rx 580s usually at 27-28MH/s each, now down to 19MH/s each) for unknown reasons, but when I run benchmark mode the rates are back to what I was used to seeing. Is there something benchmark mode is doing that doesn't limit the cards, or is this simply just real world vs benchmark?
Do you updated you gpu drivers? Because in the lastest version you need to enable the compute config in Global Settings > GPU Workload of AMD Radeon Settings.
If you are using Blockchain drivers Aug 23, this step it's not necessary, so you have another issue.