Exploding in BETA 2

I'm testing the explode function in BETA 2, rev. a925ae0
I tried to reduce the score to only a few bars and a few parts, but at that point the buggy behaviour disappeared. This score might originate to the BETA 1 version, I don't remember. Maybe the problem has to do with incompatibility. Anyway, attached is the full score with score. In bar 11 and 12 I have the following 4 part strings. All 4 parts written in vln stave, and I want to explode it to vla, vlc and cb.

So I select bar 11 and 12 of the vln stave, then I run the explode and get this:

Then I thought maybe this works like the old explode plugin in 1.3 and I have to manually copy the 4 part stuff to the three other staves before exploding. And it...

...works.

But then again, when I start a score from scratch in BETA 2, the explode works perfectly well! So if thiss appears to be an incompatibility problem between BETA 2 and any earlier version, I guess it's a minor problem and people might overcome it by some rotation through XML.