I recently was previewing audio from the toolbox, and I wanted it to stop, so I closed the toolbox. However, the audio kept playing.
Steps to reproduce:
Preview ANY audio in Toolbox.
Close the toolbox while the audio is still playing.
I had almost the same thing, when I started listening to sounds of a humanoid like jumping, walking, climbing. I didn’t pause them and closed the properties.
The only solution would be is to pause the audio in the toolbox. I reproduced the steps and got the bug.