In addon, there is an error: when you move the Dial, several empty Dial appear, while the number of columns in the group settings increases - this happens with each such movement of the Dial. You have to delete empty columns and restore the settings of the columns so that the Dial is not so small.
It is also logical to make the thumbnails from the URL at the time of saving become offline and no longer use the URL, because there is a property that this particular URL will lose its relevance and this thumbnail will need to be restored again.