Well it finally happened to us today, a clan member had logged in and checked the server about an hour ago all was fine, I logged in about 1/2 hour later, 3 Vaults full, numerous full chests, numerous benches with items in all empty.
This is on official server, several hours before raid times, no damage to building,no damage to placeables, no thralls killed, and no event logs, one positive note is they did not vacuum the items we had on us.
We found out who did it and retrieved a lot of our stuff, a player that was on the server seems to have either paid a well known player of vacuum abilities or had an arrangement with him, as much of what was taken was in locked vaults and chests of the player on the server.