Recently I was reviewing my Google analytics data and I noticed the traffic drop for February 9, 2015.
I check my web servers access logs and there was no traffic drop according to access logs.
While searching further in Google, I noticed that many Google Analytics users faced the same issue on February 9, 2015. Many users had reported the same issue in their official support forum.
So far, I am still seeing that traffic data is not updated for February 9, 2015.