I noticed this un-delegation this morning, and just posted it a couple hours ago: https://steemit.com/steem/@fernando26/my-delegated-steem-power-disappeared-today-happened-to-anyone-else
I suppose steemit is taking back delegated SP for new users or something like that. What I would have expected is to read some (official?) information notifying this would happen.
RE: Steemd.com seems to be missing data after un-delegating many users of Steem Power