I had a rest a few weeks back that cooked with charcoal, a big pit in the middle of the kitchen. To make a long story short, no chemical we applied would have any effect on the grease, actually dawn dish soap actually helped a little. The filters were clogged shut with grease. It was like cleaning axle grease out of them with only hot water, very frustrating.
Everything you did resulted in a huge mess, the grease would only move from one place to another, never rinse away. the best method for cleaning the hood was to scrape it down, and wipe it with rags. We just threw them away afterwards. Could the charcoal dust mixed in the grease have neutralized the chemicals we applied?