Keynote to PowerPoint conversion issue

Hi There,

For several years now, I have sent to my students (who learn English and all use PowerPoint), a converted file from Keynote, every week.

That presentation shows a text (in English) and an audio button allowing to listen to the read text.

More recently (as Apple came out with El Capitan), I added a second button allowing to listen to the translation as you read the English text.

Since then, we have a conversion issue. Apparently, this was a mistake from Apple as it has been corrected in the last update. Nevertheless the problem remains.

Could anyone tell me what is the clue ?

Christian