I know this issue has been partially covered regarding hifiberry dacs and volumio 3, but it’s not clear that the previous hints apply to my case. I have a pi2aes i2s board on a pi 3b+ and just applied the recommended 3.742 upgrade. The DAC model setting specified by the pi2aes maker is “Allo Digione”. This has worked in the past, but after the upgrade the Mixer Type option has disappeared and is now “undefined”. The i2s setting in config is “dtoverlay=allo-digione”. The device still works, but no option for hardware/software volume control is available. Thanks for any advice on a fix (or maybe I just need to wait until a new version is available).
Try to set headphones as output. Save. And now set your dac.
Or You can try the configuration wizard in system page.
Thanks very much for the suggestion! That does seem to work. I’ll have to remember to do this when want to use software volume control.