I had the same issue, fully working when I configure I2S, after reboot same error.
I found that post talking about editing the confi.txt file and remove the last line with overlay comand.
After that the sistem works good also after reboot, the volume is a bit lower but nerver mind.
To restore the volume control in settings->playback select the mixer type and the volume controll is restored, not completely (at 0 is not mute) but you a bit of controll.
I tried reboot several time without issues.
I think it’s a driver issue because there is no available dedicated DAC2PRO driver instead of DAC+Pro.
I hope the compatibility will be added soon to use full power of the DAC2PRO.