When deleting files in a folder LR often will not delete one file, even though it is not being locked by another program. This behavior, at least in Windows, has been present for more than 8 years. Please, please fix this.
If you select multiple images in the loupe view thumbnails you can only change metadata on the first selected image. You must change to grid view to change them all. However, other actions, like remove or delete work on all selected images while in loupe view. This inconsistent behavior is confusing. Please enable selections for all activities in loupe view.