I have the new Z12 Ultra on test for a couple of days. There seems to be a bug in the Bluetooth software.
Paired my earbuds - 1st day worked. After that, do not. Its not the earbuds as they work with all other devices - says connected/paired for audio - yet no volume. Restarted the box & the earbuds - deleted, re-paired, no difference - no volume/output/