My 'Blushing Bride' is planted in acidic soil (Red clay) and always has White blooms, with a pinkish tint and matures to pink flower. See link below.
The site even recommends that an acidic fertilizer be used.
That usually means one containing a small percentage of Sulphur(S).

Have you considered that the plants you have were mislabeled?
If they don't produce white flowers upon opening, IMO, you don't have the true BB.

Here is a link that might be useful: Blushing Bride

yes they were white and in bloom when planted!!!!