Justboom DAC Zero working in v3 beta but not v2

I run on a Raspberry Pi Zero, and had success with a HiFiBerry Zero DAC, but wished to upgrade to a DAC of comparable form factor but also having digital volume control. I obtained a JustBoom DAC Zero pHat, and found that after making the appropriate configuration changes for the new device, no audio comes from line out even as the system shows a media title playing. Testing with Volumio 3 beta, however, I found that audio plays. I compared settings for playback, and found the difference persists even when settings are matched on the two installations.

Unfortunately, running the latest build on Volumio 3 beta is not a good option due to other glitches (e.g. titles play directly. but never get added to queue).

Tested installations are with the latest images of Volumio 2 and 3, that is versions 2.882 and 3.073 (beta).

As stated, hardware is Raspberry Pi Zero (WH version) and JustBoom DAC Zero.

I would appreciate any suggestions for trying to understand how to get the version 2 installation playing audio the same as the version 3 installation.