From FG:
The compound co-axial rotor design flew for the first time in March, and has since made just two additional sorties, putting it well behind the rival Bell V-280 tiltrotor, which took to the air in December 2017.
From Sikorsky:
"We were hoping that we would be flying more," says Dan Schultz, president of Sikorsky.
Initial delays were caused by a third party that is producing a gearbox component, and the airframer is now working to catch up on the schedule slip.
Controls, transmission and rotor design have been validated by the flights so far, says Schultz, with "minimal vibration" detected.
So only three flights in three months confirmed. Appears they haven’t done anything beyond hover and very low speed. If this is the case nothing of the design has been validated and the vibration claim is no better than saying it is smooth while being towed. These kind of statements are the type made trying to keep LM from pulling the plug on funding. (Remember LM is on the V-280 where they have already seen the full capabilities of the aircraft and their products demonstrated to a timeline set back in 2015.)