Cannot play sound from built in speakers and headphones at same time + cue issues

Hi,

I have been using my DDJ 400 for a year or so now with no issues. I recently got a new MacBook Pro (had been using my brothers, same model) before. I installed rekordbox and am having issues.

SETUP:

MacBook Pro 13" 2019

DDJ 400

Rekordbox 5.8.5

Manhattan USB Hub to connect DDJ 400 & USB

ISSUE:

I am unable to play music out of the built in speakers while listening in my headphones. When I mess around with the settings I can manage to either play the music from my built in speakers OR play the music from my headphones.

Here's what it looks like when its playing from MacBook built in speakers only:

Here's what it looks like when its playing from Headphones only:

When playing from headphones only I also have a second issue, and this is that I am unable to hear sound when using the cue buttons. I cannot hear anything in my headphones when using the cue buttons as I normally would. 

SO - I need help to figure out how I can play music through both built in speakers & headphones. THEN, I need help resolving the issue with the cue buttons.

Your help is greatly appreciated. Thank you!