I'm in the same boat as you are with no loss for June, (but I have had a few indiscretions, so mine has not been an honest to goodness plateau, but possibly sugar Sunday induced.) Though after averaging my calories even with the few not so good days, I have still been well within the "losing range" IMO.
Anyway, I was looking back at my food/weight loss journal that I have kept for the last 16 months and I noticed something very strange. Last March is when I started counting calories and for the month of March I had a great loss, then April was killer, and May was super....but then June rolled around and I had a very low weight loss in the scheme of things. Once July hit another great weight loss month, August was good too...etc.. I also have pretty bad seasonal allergies and I noticed in my gardening journal that last June and this June the pollen counts have been unusually high around here. IDK, and I am certainly no scientist, but I just have to wonder if my histamine levels (and the fact that I can't breath well in June) have anything to do with it. So how is your pollen? LOL