Here's what I think went wrong with my pruning. When pruning fruit trees, you are taught to cut just above a bud and not leave a long stub. However, this does not seem to work well with hardy kiwi vines, at least young ones of the Issai variety. I cut just above the last bud and what happened is the top inch or so of the vine dessicated (shrivelled and dried), killing the bud. Other buds further down are doing fine. So, it looks like it's best for hardy kiwi NOT to prune just above the bud, but to leave some vine above it!
Also, I have read some conflicting information about pruning hardy kiwi. Some sources say prune when the plant is dormant, well before spring growth, otherwise the vine will bleed and cause damage (perhaps that's what happened to me). Others say don't worry about the bleeding, it doesn't do any harm?!!!