TTS in sentence mode - no audio playing

I tried to use sentence mode for my android app but the audio won’t play. I alternated between samsung and google tts but it’s the same result. Words tts is working.

Ps seems to be only in korean. I tried indonesian

Do you have that problem with specific lesson only, or you can’t play sentence TTS in any lesson you open?

Lesson 7 of the mini stories in Korean seems to be the only one with problems. Normal audio and TTS on individual words works

Actually, no… It now happens in lesson 8 too. The first sentence is working, but if I move on, the audio seems to disappear and not work anymore