XDJ-XZ deck 1 & 2 different volumes when recording on Mac

I've noticed an issue with the XDJ-XZ when recording on a Mac and I'm wondering if anyone else has come across this.

Mac is Catalina 10.15.7 . I have the XDJ-ZX driver v1.0 installed. I'm using OBS to stream the output.

The issue that I'm seeing is that the audio volume and filter sounds different on deck 1 compared to deck 2 (which is quieter). I've tried this while playing from Rekordbox and from USB, and get exactly the same. I've even tried setting up on another Mac. Again, exactly the same. 

The master output from the console to the studio speakers is fine, and recording on the console (USB) is also fine. 

The only conclusion that I can reach is that there is an issue with the driver.

Has anyone else experienced this ?