Bose NC700: Volume with Aux & NC on

[kavak]

Bose product name

NC 700

Country

Europe

Firmware Version

1.8.2-11524+e0f7590

App Version

4.2.4

What devices were you using that were affected and what version are they on 
Laptop (Linux) Smartphone (Android 9.0)

Detailed description of the issue and steps to reproduce

I just got these headphones yesterday, installed the latest firmware and suffering from this vexing problem:

When the Headphones are on (for example noise canceling is active) and the headphones are connected to the music source with the provided aux cable, the volume is very low/feeble. 

This is issue is similar to that reported here (https://community.bose.com/t5/Around-On-Ear-Headphones/Sound-becomes-very-feeble-when-connected-usin...) but the solution provided at the link, does not address the problem (I confirm my HP are on).

Are you able to experience the same problem? Can this be fixed by using another firmware?