No audio prompts and music stops

Lately when I get a audio prompt during a workout I hear nothing. 

And I have to tap my earbud to continue the music. 

I haven't changed anything in the settings.

Software version 11.28

Is this a bug or has anyone a suggestion to solve this? 

Also last week the watch went white during a run. After a vew minutes it was okay again. Luckily the data wasn't lost.