It may not be budkill that is preventing the flowering. A location in too much shade or improper fertilizing practices can have such a result as well. Also, pruning at inopportune times or too severely can have a similar result.

ASB is supposed to be a remontant (reblooming) form that can produce flowers on both old and new wood. However, hardiness trials related in Dirr's Hydrangeas for American Gardens indicates that the reliability of flowering, even on these so-called remontant types, is heavily influenced by weather, particularly wide fluctuations in late fall and early spring temperatures. With the late Easter freeze that much of the eastern half of the country experienced this year, I'm not overly surprised that flowering on any type of macrophylla was affected. For safety's sake, in zone 5 I'd consider some sort of winter protection (as outlined excellently in Hayseed's winterizing thread), as well as paying attention to location, fertilization and pruning.