Filepicker inside a list

I am trying to have a list auf items, one should be a an image. So I trying to achieve that with the filepicker. The problem is, whenever I hit the save button, the chosen image not chosen any more, so its basically not saved.

Outside the list, I can very well save the filepicker.

Anyone knows what I am doing wrong?

here is the exerpt from the blueprint:

          name: videos
          type: list
          style: vertical
          label: Videos
              type: title
              label: Titel
              type: text
              label: URL
              type: toggle
              label: Zeigen?
              highlight: 1
              default: 1
                  1: 'Ja'
                  0: 'Nein'
                  type: bool
              type: filepicker
              folder: '@self'
              preview_images: true
              label: Select a file

@jacfab This seems to be a copy/past induced problem… Try renaming the field’s name from ‘.header.a_file:’ to ‘.a_file:’ and it should work…