Process -> Slide: Envelopes not sliding along with selected tracks

In the track or PRV view, when I select parts of tracks and slide them forward or back (using the process -> slide menu option), the envelopes don't slide with the rest of the data. 

Alternatively, when I use nudge instead of process -> slide, the envelopes *DO* slide with the rest of the data.

Am I doing something wrong?

Thanks!