Hi!
I had this happen to me also, and I just kept going (it was very hard to keep going with no reward on the scale) and after a few weeks, the losses started happening again. So my advice to you is to just keep going and don't give up! I know, that's not really helpful.
Are you doing PointsPlus? You could try switching to FillingFoods (or is it called Simply Filling? I can't remember right now) and give that a try.