That's how it worked in prior games. And if you do that in III, it will send them sprawling, but it won't do any damage.I don't have to hold the button... a quick tap of B when they go for a swing, it counters
Only if you don't issue a follow up command right after the counter. Red triangle appears over enemy. Tap B. Game slows down. Tap X, enemy dead.
I really don't understand what you must be doing wrong but the way you're describing the combat system does not tally with how it works in my experience :/