[Bug?] All audio player device work on starting Round 2 and later Round in a game

Hi,
I have a question about audio player device and whether the title problem is bug or not.
I created UEFN game, in which settings are:
[island setting]
Total Rounds : 25
[audio player device]
Enabled During Phase : Gameplay Only

I set about 100 audio player devices on the level.

When playing this game, after Round 2 and other later Round (on Round 1, this problem not occur), all audio player devices work on Round starting - while I just set in this project to execute its “Play” method on verse code after game starts.
(The attached movie show)

Is this a bug or its cause lies in the setting?

Regards