As a followup, the documentation at https://fmhelp.filemaker.com/docs/16/en/ddrxml/#themes doesn't mention that Styles can be deleted. If it's deleted, but not saved, there is an additional attribute of
in the XML.
And to clarify one more. They appear in the LocalStyles section as deleted, but in the Theme, the ones with no name persistent after the theme is saved. So that's a bug that the related style doesn't also delete.
Thank you for your posts and observations.
I have forwarded all information to our Development and Testing departments for review. When I receive any feedback, I will let you know.