Confirmed that this is fixed in 15.4.6151. The Delete button now works and the Download button is gone.
However, there is still an issue. When you Edit a contact then click Delete, it closes the window and shows a bunch of N/A's where the Contact info used to be. It should move to the next Contact like it does when you click Delete without going into Edit mode first.
Suggestion: There are at least 2 other ways to delete a contact, so just replace the Delete button with a Cancel button to abort the Edit.