[String]

My mates vyper does this a LOT and mine sometimes.
Doesn't appear to matter what software version you use (v1 or any of v2).

It seems to be salt or dirty contacts as quite often simply cleaning the bottom of the computer with water, drying and meths then connecting the cable, making sure its snug seems to work.

It maybe it misses dives if it gets a slight interruption in the transfer and truncates from there. The download itself is just a simple memory dump so thats possible.