When highlighting a set of MIDI notes to change to double time in particular, I used the logical preset resulting in notes moved to a random bar, with most notes starting at the same point.
I have provided 2 jpg files showing the highlighted MIDI notes I wanted to change to double time along with the result.
I have no idea as to how this could be happening. I did indeed trash my preferences afterwards and repeated the process and the same result came about.
I also tried starting a new project and re-recorded the notes from my MIDI keyboard and the same error happened.
If it matters, I use the Yamaha portatone WDM USB MIDI driver in order to play my MIDI keyboard into Cubase 6.
This is a really strange and annoying problem, please address this issue ASAP, Steinberg.