Re: feed consumption question
I had the same sort of thing happen this past summer. Difference for me was type of hive. one was a lang the other a top bar. syrups was all made in one batch and fed in the same type of feeder. lang bees took right to the syrup. top bar bees ignored it for two weeks straight. Top bar bees continued to ignore syrup right up to the point they where running out of honey. Finally I realized there was an access issue for the bees. even though there was a gap under the follower board. It apparently was not big enough to suit my bees. they would not go under that board even though it had been designed for just that purpose. I modified the follower board to have a larger gap and the bees took right to the syrup.
I don't think you will have the same problem. but it could be a similar problem. at the very least take a look with an inquisitive eye at what it would be like for the bee to get to that syrup. maybe something just isn't right for them.
All work and no play makes a happy bee.