Error message "ON will save only the available pages" when synchin

[Roadtrekie]

I get the error message: "Some pages cannot be saved because they are not
available or may not have synched. OneNote will save only the available
pages" when trying to synch. What does that mean? Will I lose any
information if I go ahead and synch anyway?

I get a sinking feeling every time I screw up this synching thing.

Thanks for any help.