Feed take-up sporadic

I went to the London site today with the aim of putting back on each of 2 hives the Apiguard tainted honey supers which I'd removed last week. The plan was to remove the contact feeders I'd installed last week and leave each hive with a crown board with a restricted feeder hole above which there were 2 empty, frameless supers with the super of honied frames above that. In theory the bees should take the honey down into the brood box from there. However, I was surprised that whilst this worked for one hive, on the other I found the contact feeder still mostly full. I checked it for function: it seemed fine, with syrup dripping out the bottom when I shook it. Weird - I guess these bees (Hive Amidala) were just preferring the ivy nectar flow instead. Good for them. I left the contact feeder in place and stored the honied super hidden from the bees above that, which I will give access for on my next inspection.