Spotify blocks every output sound from other apps when playback is stopped on bluetooth

[nico_1111]

Device

Macbook Pro Mid 2015

Operating System

MacOs High Sierra 10.13.4

My Question or Issue

When I'm connected to my speaker through bluetooth and I stop the current playback in Spotify the output sound of every other app is muted. But if let the playback run and I just lower the Spotify volume to zero I can hear other sound playing from other apps, such as Youtube if I want to play it. It's as Spotify playback controls the output sound of my Mac, if playback on sound is allowed to reach my speaker, if playback is stopped no sound can leave my mac.

A comprehensive video is attached.

Thanks a lot!