This sounds just like how things go where I live believe it or not. Basically its all happy buzz buzz until the party's over. When the last of the nectar dries up and the robbing starts, it's like flipping a switch. The demeaner of all of my hives changes almost overnight. Hives that I can open all year long that just ignore me, all of a sudden become mean and nasty. My robbing isn't large scale gang fight style but it's definately noticeable with low numbers of scuffles on the landing board and in the dirt when they fall off of the landing board.
I have always found that I can reduce the amount of fighting by reducing the entrance but not quite completely eliminate it. This year I made and installed robber screens and opened my entrances all the way. I went full open because I run solid bottom boards and as of late my condensate has increased a lot with the lower temps (don't laugh, we're hitting the thirties a lot lately at night with frosted rooftops and a little windsheild scraping). This is the first time I have used the robber screens and I wish I had done it sooner, they work as advertised. If I were you, I would put robber screen on and I think your troubles will be over.
Old Blue
Punishing taxation with no representation in
Kali-bone-ya