Strange Divisi-Playback

I have arranged my string section to consist of three small ensembles and one solo instrument. Normally, I do this in Vienna Ensemble Pro. This time, however, I attempted to set it up using independent voice playback and the divisi function.

As you can see in the video, this approach has led to some issues: When I input a line and switch to unison at a certain point, the playback works as expected. However, if I make changes within the unison section, the playback still reflects the old version—even if I delete notes entirely, as shown in the video. Additionally, when I enter new notes, not all instruments play as I would expect in unison; only the first instrument in the list (in this case, the solo violin) sounds. When I return to the unaltered notes, all the instruments in the group play together again.
Is there a setting I can change?

This might be the solution to avoid the notes playing back.

So I have a feature request to, that I made some years ago: would it be possible to allow users loading more than one instrument to one Staff? In other words.: I would love to enable independent voice playback with as many divisi sections / Solo instruments as I want to. They would all play in unison as long as I only type in notes into one staff. As soon as I notate chords or enable divisi or add voices they would split up.