How long have they been planted? if just this year that is not unusual. are the tubers just/barely covered with soil? if they are too deep they wont flower too well. I must admit I don't feed mine and they do flower well.
Sometimes the weather affects the bud development. so if buds started then they died/rotted that is down to the wet bit back in the spring.

best to leave them alone and avoid temptation to lift and re-site. See how they do next spring.

If you do decide to move or replant them, the best time is immediately after the top growth has died off. They start into growth below ground well before any top growth appears in spring

Thanks for the advice, I have planted them so that the tubers are beardy covered, some of them are this year plants and the buds that rotted and died were from the new plants, will see how we get on next year.

They also like the sun.