From my understanding of hydroponics, you will always have a die off when you take soil roots and place them in water. They are different types of roots, and water roots have to form.
It only takes my pothos plants less than a week to start sprouting new roots in the water, and I keep the plant potted, so I have an endless supply of the vines. Frequent pruning of the growth tip will promote more compact, bushy growth, as well as higher nitrAte absorbtion.