Can't change "Output Device" to installed DAC

[buckaroo]

That command output looks ok to my eye.

You could also try verifying that cardnum is 1 and that the correct overlay (hifiberry-dacplus-pro) is loaded in config.txt

Code:

sudo moodeutl -d -gv cardnum

cat /boot/firmware/config.txt

Other than that I can't think of anything else that could be causing the issue you are experiencing.

"I can't change from "0: Pi HDMI 1" to "1: HiFiBerry DAC+ Pro". When I try, it just reverts back to the HDMI entry"

Both confirmed - this is just weird. Oh, well, it doesn't seem to be affecting functionality, so I won't sweat it.