Problems reorganizing terms using drag-and-drop handles

I noticed some issues with the drag-and-drop reorganization functionality on the list view of a vocabulary. I have provided examples below. Please let me know if they are not clear.

I created a new vocabulary with 3 terms under root:
a
b
c

I then move b & c under a
a
- b
- c

I then try to move b & c back to root
a
b
c

I am able to drag b & c back to root but when I click save, the hierarchy does not update. b & c remain under a.

I create a new term d
a
- b
- c
-- d

I then try to move d to root
a
- b
- c
d

I am able to drag d back to root but when I click save, the hierarchy does not update. d remains under a.