Hi,
I have a RP4B and a original Hifiberry Digi2pro HW2.1 used with LE 10.0.3.
I tried first
dtoverlay=hifiberry-digi-pro
in the config.txt as printed on the HAT
then I used
dtoverlay=hifiberry-digi
as decribed here Digi2-pro not found
Unfortunately in both cases, it doesn't appear in the system->audio settings.
Any suggestions what the cause is?