I have been playing around with split and weld all afternoon and have found this.
 When I import a pz3 and split it, it will fly into many pieces.

Using psoer import options I uncheck Group figures as single meshes and uncheck Use quaternion interpolation.  I check import single frame.

 When I attempt to split this pz3 it explodes into many pieces.

Now if I weld the pz3 before doing the split it will then split as it should.

If I leave group figures as single meshes it makes no difference with the spltting of the file. It still explodes. :(

I know this is a work around of which I hate the phrase but it may be only way to accomplish this untill e-on gets it fixed in next update.   Previous builds didn't behave as this build and we didnt have this problem. :)

Same thing with a saved vob.  It needs to be welded first  and then split to keep from exploding.
  If you bring it in to vue and split first it will explode.  If you dont weld first and do a split it will explode.

This was using the Golden_Hind ship that was saved as a vob.
 

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