DinoBot

This is actually happening to me as well. To describe a bit more in-depth (at least for my issue). It seems like the extruder starts to push filament through and print before the nozzle is making contact with the print bed. This causes a portion of the raft perimeter to not print and subsequently provides nothing for the supports to stick to so they curl or drag with the nozzle marring the raft. It looks like it tries to start printing while moving to the starting position but while the z axis isn't far enough down.