JabRef 4.0-dev--snapshot--2017-08-02--master--63414b030
Windows 10 10.0 amd64
Java 1.8.0_66

Steps to reproduce:

1. Type last name of the author say "Lastname"
2. A suggestion pops up "Lastname, F." and you can already see the item you want in the list
3. You hit enter, no item is found

This happens in particular if the author field is encoded as e.g. "F. Lastname and G. Rdsfdsf and Z. Ddslkfjddf" instead of "Lastname, F. and Rdsfdsf, G. and Ddslkfjddf, Z."