Ok so it does it in Cubase 6, Studio One and in Stand alone. It does it on all 3 studio machines. This is 100% reproducable for me. I created brand new empty songs to test this with, that had no mappings of any sort at all.
Start an empty song, create only one track with VI PRO 2. Put Solo Cello Sustain Porgressive Vubrato patch in the first cell A1. Then add Perf-Legato-Zigane in cell two A2. Turn on key switching for X Axis.
Now create one very long note assigned to the progressive vibrato note and then do a fourth below note for Zigane. It will not play a slide, it will come clunking in. Now stop the playback, change the VI PRO player back to the progressive patch by selecting it. Now, move the marker just before the zigane note and hit play, it will play the zigane (be sure to start playback at the point where the keyswitch note changes it from sustain to zigane, mine is near the start of the zigane note). If you move the playback head to close to the beginning of the sustain note, it will not play the zigane slide. The key though is when you hit play it must start sounding the sustain patch, before it key switches to the zigane. So be sure to place that keyswitch near the zigane note start time.
Maestro2be