It looks like AudioPlayer does not fully support http2.
Way to reproduce in a custom skill with Audioplayer:
1. starting Audioplayer in MyPlayerIntent, with a mp3 hosted on cloudfront with http2
2. AudioPlayer is starting and playing the song
3. Using AMAZON.NextIntent for the next Song
4. Adding next Song with with REPLACE_ALL PlayBehavior
Current song is stopped.
Next Song is not playing.
No error from Alexa.
To fix this problem, I'm using now http 1 in the cloudfront settings.
But I think, that Alexa Audioplayer should support http2.