I have found a reproducible bug in the UM^2 firmware. After you abort a print, while the build platform is still lowering, quickly go Back to Main Menu -> Maintenance -> Advanced -> Move Material. The buildplate will begin to rise, and will not stop even after crashing into the nozzle.
I am running the latest firmware released with Cura 13.12
Here is a youtube video I uploaded of me reproducing the bug.
Anyone else able to reproduce this?