Thank you for writing this post.
We have attached a sample SLDPRT file which we used for testing and it works on our side. You could try this.
The output assembly should be created with following Structure in "Feature Manager Design Tree" as seen below.
Each Body is saved as a part in the Destination Folder
We would like to ask you for more details and it would be great if we can communicate using #TASK Feedback form which can be initiated as shown below or email at email@example.com
4Bodies.SLDPRT.zip 59.0 KB
Looks like there was something wrong with my Default File Locations so when it was completing the Save Bodies it didn't have a template to use and would fail. I replaced that file location with the file that contains the rest of my templates and it seems to be working now.