Yesterday, using beta 39, I selected a couple of paragraphs and added a comment.
The text highlighter with a yellow background and blue underlining.
The comment box was added correctly in the right-hand column.
After updating to beta 40, I decided to delete the comment. At first glance, it worked and the highlighting of the text disappeared. The comment box also vanished.
Unfortunately, the comment box keeps reappearing. Moving the text to another scene document makes the comment box follow along.
The downside to reporting problems on this forum is that it seems fairly arbitrary whether someone from L&L notices the post.
If they do see it but can’t reproduce the issue, it would be useful if they said so. In such cases, we could investigate further at our end and post updates.
That said, I have the same issue with the beta / bug forums for, say, Affinity Publisher.