Reorder field does not work on new element

Reproduction path:

• open a document that has a multiple ordered field. The field should already have 2 entries. It can be a String field or a Docbase field for example.
• add a new entry: it appears as the last entry of the field
• click on the 'single arrow up' of the new entry to move it up just one position

Result: the entry is not moved.

Expected: the entry is moved up one position.

Notice that the 'move to top' arrow does work! After saving and reopening the document, the bottom entry can be moved (workaround).

It may have to do with the fact that the field is empty. Another strange effect, that may result in people lose their data:

Reproduction path:

• open a document that has a multiple ordered field. The field should already have 2 entries. It can be a String field with values 'a'  and ' b'.
• add a new entry
• click on the 'single arrow up' on that last entry (nothing happens)
• type a value in the third empty entry (for example 'c')
• blur the field

Result: there are three entries: 'a', empty and 'c'. The value 'b' is now lost! So it looks like the values are swapped, but the change is not displayed.