Youtube Video is not shown after migration from json source into my content type song

The Youtube Video is not shown after migration from json source into my content type song with an youtube field.

The migration is carried out successfully and correctly. After the migration in all my song nodes the youtube video url is correct (e.g. https://www.youtube.com/watch?v=CORREC_VIDEO_ID).

But on my nodes the Youtube video is not shown (video_id is missing in resulting iframe html code).

If I edit and save my song node (without making any changes) manually, the Youtube video is then shown and can be played.

I have a lot of song nodes with a youtube video field, it is not possible to save all these nodes manually.

How can I solve this problem?
Can you help to write a patch?
The goal is: After migration into my song node type all Youtube videos should be shown without having to save each of the song nodes manually.

Thank you.