Very astute observation Zen1…and not a nectar placement pattern exclusive to Flowhives…traditional hives show this absence of filled cells immediately above the queen excluder also.
In my experience, this pattern existed in most of my Flowhives even if there was a honeyflow on and with very strong hives…so I really scratched my head. What was going on here? Thanks to this forum I may of found a solution when Michael_Bush suggested excessive empty cells above the queen excluder may be related to an inadequate drone population. He had a point as in my case I had traditionally, vigorously culled brood comb so brood chambers contained next to no drone cells…just worker cells. I wanted worker bees…I was after honey production. There were other reasons for this vigorous culling also.
So the next season I inserted these drone bait combs on the outside frames of my single brood chambers.
Perfect drone comb was built out in every case…and it appeared that the bees stored honey much more readily above the queen excluder. It will take a few more seasons to confirm this absolutely.
As a side note, these drone bait combs are also varroa mite bait combs…a biological way of controlling the mite. Those mostly foundationless brood combs can be simply treated as a comb honey frame…cutting it out of the frame…and in this case discarding the varroa infected comb. Also I now could restrict drone development to individual frames instead of dealing with drone comb on all the bottoms of the other brood frames…actually making beekeeping much more enjoyable.