My Face ID with mask not working

I updated my iPhone 13 Pro to iOS 15.4.l last night and was excited to try the new Face ID with a mask feature, but I can't figure out how to make it work. I have reset it several times and each time it does an initial face scan and then asks to do an alternate face scan. It doesn't indicate whether or not I should wear a mask for the second scan. However when I try to do the second scan with a mask on, it doesn't even acknowledge there is a face to scan, so I have to remove the mask and do another maskless scan. Then when I wear a mask, Face ID doesn't work. What am I doing wrong? I am using a black KN-95 mask, which is the only mask I currently wear. I try to make sure enough of my eyes and nose are showing without removing the mask, but nothing makes a difference to get Face ID to work except for not wearing the mask.

Make sure that you have updated your iOS to 15.4. Then see this, Use Face ID while wearing a mask with iPhone 12 and later - Apple Support