Spotify going silent when Powerpoint slideshow runs

[Hebrews12]

Plan

Premium

Country

 UK

Device

Laptop

Operating System

Windows 10

My Question or Issue

 I've been playing Spotify bin the background while having a Powerpoint slideshow running for many weeks now but today it has decided that as soon as I run the slideshow, Spotify goes silent. The songs are still playing, you just can't hear them.  Has anyone got an idea why this might be happening?

[ZU420]

Make sure that your audio output is correct. When I open PowerPoint into presentation mode it switches the audio output sometimes. (e.g headphones to hdmi)