We'll need to get to the bottom of this NOAA/webcast situation.
— Chris Bergin - NSF (@NASASpaceflight) March 30, 2018
SpaceX says it was "their restrictions"
NOAA say "Wasn't us, guv!"
Smart money is on a NOAA plane (unavailable today) providing a link between the second stage and ground stations, but we don't know for sure.