Lack of moisture could kill the flower buds. It is the first thing to be aborted when moisture is lacking. But I would have expected some wet years in that 10-year span and therefore blooms in some of the 10 years.

Winter and pests the two things which can reliably kill flower buds though. What zone are you in? Hydrangea anomala sp. petiolaris should be able to handle most if not all USDA Zones in NY, provided you do not have a microclimate that would somehow drop temperatures into Zone 3 territory.

I am not sure how big/tall these shrubs are now but I somehow do not think pests would have been able to get at buds near the top of the shrub (squirrels are the only exception); and you might also have noticed the buds suddenly missing in such a case.

Climbing hydrangea needs some fertilizer once a year or so but nothing outrageous. It should be fine with some manure, compost, cottonseed meal applications in June. Too much fertilizer could keep the plant in growth mode when winter is near and early frosts might zap flower buds so I would not feed it after July. If concerned about nutrients, I would make a soil test to determine if there is a defficiency in this area.

Luis