I've done several Pack an Go's recently and I've had a part not take on the new name I gave it in the Pack and Go. What's happening here? You can see that I renamed the part to "P+G Test Part.SLDPRT" but it keeps "TPN170217011.SLDPRT" (see folder view for result of this Pack and Go, second image). The assembly renamed as expected. Other parts that I have renamed in the Pack and Go before do get renamed (not shown in this demonstration). I'm using SolidWorks 2016 x64 SP 4.0.