I’ve been uploading new songs to Hooktheory for the past few weeks, and sometimes when I upload a video their thumbnail isn’t shown in the search results, and instead they show up like this. And this applies to many songs that I have attached a video to, so do they just take time to show up?
Please do not tag me in your forum posts unless I am personally involved in an issue. It is sets a bad precedent for the forum, and presents the unfair implication that your issue is more important than issues of other community members.
The broken thumbnail typically happens when the youtube link is not shareable (either in general, or in your country), or if the video has since been taken down. You might verify the settings of the video on the youtube page to see, usually it’ll say if the video is not shareable.