Kindle app: downloaded book cannot be removed

An ongoing problem: some books do not respond to Remove Download. My issue is NOT how to remove the books, my issue is that this problem has been going on for a long time. Of the 250 or so books actually on my iPad Air 3, a half dozen or so are not removable.

Now, I know how to remove them, but it's a drastic solution. What I would like to do is bring this to the attention of Kindle App v6.65 support and ask them to correct this. If anyone has an idea how to do this, please respond. Thanks!