My Analog Discovery 2 was very sensitive to movement, with Waveforms reporting the connection lost at the slightest bump. Merely manipulating the flywire leads was enough to cause a disconnect.
I determined that the plug on the USB cable that came with the AD2 was not able to seat completely into the AD2's USB jack. While looking through the top of the AD2's enclosure at the USB jack, I observed that the two metal "spring fingers" atop the USB plug were not inserting deeply enough into the jack to permit them to raise and latch into their corresponding holes in the top of the jack.