That’s a huge bug not only for latest firmware but has been existing for quite a while in 5.18.6. I reported on reddit and seems many users are suffering from this.
https://www.reddit.com/r/kindlescrib...d_my_notes_it/
If you are using Mac, I have just updated my App KMate(free)to auto clean these and keep the right one. Let me know your clippings become clean.