the version 2.7.0 copies the table border properties not well. After a slide copy they are missed within the new one. Its not possible to set this properties again.
The version 2.5.0 does this issues well !
Thanks for your interest in Aspose.Slides.
I agree with your issue and it has already been added in our issue tracking system and is under investigation with ID SLIDESJAVA-32116. I will share the further response with you as soon as the issue will be resolved.
We are sorry for your inconvenience,