DietPi Roon Bridge HDMI out downsampling why?

Hello All,

just loaded DietPi to my RBP, am impressed.
A breeze to set-up and am getting sound immediately.
Set-up as soundcard device HDMI
I have connected the Pie through a HDMI to a receiver which states its supports 24/192 and SACD streams.

In the setup I see the following

Which is better then expected

However when I play a hires file I see the folllowing:

The 192kHz seems to work, but the bit depth gets reduced to 16bit.
Did I perhaps forget to set something up correctly?