CC button issue

Hi I've got an issue with the Storyline CC button.

Sometimes it is present on the slide, sometimes not.

I checked everything, there is captions on the sounds and it is available everywhere.

It seems to be random, it disappears of some screens if you play the module, and the next time other screens are concerned.

I opened a ticket but I've got no answer from the support, they uploaded my module on the scorm cloud telling me that it was ok but no, the issue is also on the scorm cloud.

Any idea please ?

Here is a screen where you see that the caption is here but the button vanished :

PS : It's a really simple module, with no layers, only sounds (one per slide) mouse cursor, pictures and shapes.