The fares from your previous examples have been withdrawn, so I can't verify. But if you run into this issue again, pls send me the details and I will look into it further...
Different, but same kind of issue:
On KLM website, I found a special Holiday fare in business at 967 GBP (without taxes) from EDI to BOS (12/23-01/03)
I can't find it on Sabre fare dot/res (neither on ITA...)
No fare code on KLM site.
So some fares are not published?