Assembly sub-assemblies not saving with save all

I have a chain of assemblies one built from another and when I am trying to save I get a pop up stating that the underlying sub assemblies and some of the part are not saved.

SW gives me a list of the documents that have to be saved. I select save all and the document saves.

The next time I open the same assembly the referenced files show again as needing to be saved, again.

I then opened each of the files individually (both parts and sub-assemblies) to save them and then saved the chain of assemblies.

The next time I opened the assemblies, the same files where listed as needing to be saved again.

Why isn't SW saving these files?

Working In SW 2021 SP 2.0.

SolidworksModeling And Assemblies