I noticed that too; My best guess is that the display just sticks to what it last knew if it doesn't get any updates, and the leaking LOX from the 2nd stage caused enough damage or interference to interrupt communication. It's at least my assumption, since the 1st stage continued to fire (i.e. accelerate) until some 8 seconds later, according to the NASA report [1] (Page 3)
[1] https://www.nasa.gov/sites/default/files/atoms/files/public_...