Many thanks for your comments.
My husband has been very particular about the temperature so I don't think that is the problem.
Its difficult to candle them because most of them have very dark shells and its very hard to see inside.
Humidity is aok too, I think but I would have to check with my husband.
Think we will leave it going a bit longer?!?
One has a tiny crack on it but then there has been no change for a day or two.