In Blue Origin's case, they cross the Karman line (100 km). Virgin cross 50 miles, which is the US standard threshold space, but not the Karman line. Regardless, both are suborbital hoppers.
From the live stream, it appears that the 2nd stage motor started, then stopped a couple of seconds later. If so, I'm guessing a sudden loss of power to the electric propellant pumps.
ETA: Appears to have spun hard shortly after staging.