Hydrangea leaf buds disappearing

Hello,

I have a hydrangea which I planted last spring. I pruned it back in winter after it had lost all its leaves and flowers. I’d noticed a number of leaf buds starting to appear and have been keeping a close eye in them and then today I noticed it looked as though all of them had been snapped off. What would be doing this and how can I prevent it from happening?

Thanks,

Amanda