Does save_post work to update a field in a block?

I'm having a problem with save_post and updating an ACF field in a Gutenberg block. I have a field called 'youtube_title' and need to a add some text in a field when a post is being saved. I tried to do the following:

update_field('youtube_title', 'testvbv', $post_id);

The field doesn't get updated when saving. I then added a text box called 'test' and have it shown at the bottom of the editor. When I save a post, text does get added to the field.

update_field('test', 'testvbv', $post_id);

Any idea on how to add text to field inside a Gutenberg block?

Start by reviewing the save_post hook and the update_field calls shown in the issue, then compare the youtube_title field's Gutenberg block configuration with the working test field. Done means identifying why the block field is not updated during post save and confirming that youtube_title receives the intended text.