Update December 9, 2020 = A DELL-Cares agent setup a Service Request to exchange the monitor.
I just recently purchased my AW3420DW monitor to hook up to my new Xbox X. It was working fine until today it switched to DisplayPort instead of HDMI which is how my Xbox X was connected. For some reason, the button doesn’t move to switch it back to HDMI so I cannot use my AW3420DW. Anyone know of any fixes to sort this, I ran basic diagnostics on my AW3420DW and all ok, I just cannot switch back to HDMI. Cheers 
AW3420DW, cannot switch to HDMI