If you are able to start a "Chat" session with Asus Support that will be the best way to go since they might be aware when the 400 Series Motherboards will have the BETA BIOS update to make the new 5000 Series processors compatible.
Otherwise open a Asus Support Ticket via Email.
According to Asus site the 400 series already have the BIOS update for the new CPUs. Went to your Motherboard CPU SUPPORT LIST but it doesn't show any 5000 Series CPUs yet. but the latest BIOS version 4007 mentions it is for the new CPUs: https://www.asus.com/supportonly/ROG%20STRIX%20B450-F%20GAMING/HelpDesk_Download/
I would verify with ASUS SUPPORT to make sure that BIOS is for the new AMD 5000 Series CPUs . Most likely Asus hasn't updated its CPU SUPPORT LIST yet.