100% reproducible:
1. Esc menu
2. Edit UI
3. Have "Custom HP Bar" checked
4. Close the "Level/Point information" eye in the top left
5. Click Save (ENTER)
I believe you could not hide the element without custom hp bar being enabled previously.
Now you cannot hide it at all. Even in combat focus mode, it still shows.
It's a known issue in the Notice for the last 2 weeks: https://www.naeu.playblackdesert.com/en-US/News/Detail?groupContentNo=184&countryType=en-US