Using melee while playing Umbra makes me become invisible and create an Umbra clone, very easy to reproduce

[DerGilb]

On Umbra, spam heavy blade like paracesis with primed fury and while you do so, transference in and out quick. At some point you become invisible. You can now jump through the ground.... once you are falling, transference in and out once again. You will be falling for a long time. Once the falling stops and you pop up back overground, you now have an umbra clone that fights too! Your abilities, except for exalted blade are locked for the rest of the mission though....