From the Twitter feed....
Dispatching the crew to the launch pad, however, would present a lengthy hold here at T-minus 4 minutes, but the potential to still launch today. The Atlas team has until 4:46 p.m. EDT to get the rocket airborne this afternoon.
The weather is fine and no other technical issues have been noted throughout the countdown.
The anomaly team is putting together a plan to send a special team into the pad to check the configuration of a manual valve within the mobile launch platform upon which the Atlas rocket sits. That valve could be mis-configured, and resetting it would allow the rocket to launch today.
now a range interference issue crops up.