Meditate/Charged Staff Bug

Whenever I use my Charged Staff skill to gain power from power charges, my Energy Shield (ES) drops by 469 points. My total ES (after Meditation) is 6,470. After using Charged Staff, 4 seconds later, my ES drops by 469. If I am fighting jn high density areas, I can repeat this mid-combat, lowering my own ES by the said amount over and over, hypothetically reducing my own Energy Shield to zero without ever taking a hit from the mobs.

As you can imagine this is a highly irritating bug. Please correct, so this does not happen.