JabRef 3.7dev--snapshot--2016-09-29--latex-free-fields--93e665e
windows 10 10.0 amd64
Java 1.8.0_101

1. Select an item and try to drag'n'drop it onto an existing group
2. Nothing happens
3. Adding the groups name manually to the "Groups" field of the item does work, however, and assigns the item to the group

(see also: #1993)