Successful response but Empty Content youtube transcript API

Example: issue on this video
https://www.youtube.com/watch?v=m-M_HzS4w2Q

Here you have a successful response from the API but PROBLEM:
empty array is returned in “content: []”, no transcript although a lot of languages shown are available !
"show transcript" and all languages captions are available on youtube, can you estimate the time it will take to fix all problems ? Thank you for your time and patience