Have you tried a new layout with those fields from the related file's Table occurrence (TO)?
Usually you will get the message if the underlying table occurrence of where the field references has been deleted from the graph. Even if youdeleted it by mistake and then put a new table occurrenc back on the graph, the field will not update. You will have to repoint them to the correct TO.
If you can get a new layout working then you can just repoint the fields in the orig layout to the TO that you want.
Can you explain me on " New layout with those fields from the related file's table occurrence (TO)"?
I HAVE NO IDEA ABOUT THIS...IM AT BEGINNER STAGE
A file has tables. A table occurrence is basically a representation of the table. A layout is based on a table occurrence, not a table.
I would suggest you read these PDFs to perhaps help you along...