Hello ,
Thank you for contacting us about your issue and there seems something potentially wrong with the file/scene somewhere and we would need to further investigate. Please report a bug and provide the Datasmith version you are using as well.
Here is the link to the article on how to find the Datasmith version:
https://twinmotionhelp.epicgames.com/s/article/How-to-find-the-Datasmith-Exporter-Plugin-Version
This is the link to follow to report a bug:
https://twinmotionhelp.epicgames.com/s/case-community-page
Kind regards,
Vincent B.