Soul Tether Unique not functioning

I have a blood mage and trying to use vitality siphon with ES. It has two levels of issues:
1. The leech does not apply to the ES no matter what the scenario
2. When I put the belt on with full ES all my ES disappears instantly.

Please fix. :) This would be a major crux of my build if it worked as the item states and I assume is intended.