Following the online controversy, ASUS is now informing us that it will support AMD's Ryzen 5000 series processors on its 400-series motherboards. Beta BIOS versions are expected in January 2021.
ASUS will follow AMD’s decision: beta BIOS support for 400-series motherboards will be ready starting in Jan/2021, all ASUS X470, B450 & B450 II motherboards available on the market will be compatible via a BIOS update. When or if AMD sends us the required Agesa update, ASUS will follow AMD’s support plan to release the new BIOS.Of course, it's unknown whether customer service was wrong or whether ASUS changed its policy.