Lost my exp, hence lose the streak :(
I have faced this problem several times. I completed about 2 lessons (my goal is 20exp/day), the notification showed that I was on my streak. But just few minutes later, when I checked my profile, some exp have gone, and I had to learn another lesson to maintain the streak... I don't mind studying more than I should, but it's pretty annoying since I've lost my 21 day streak thanks to this kind of issue... :(
P/s: I mostly use Duolingo on my iphone.