days strike resets without reason
I had an 81 days streak and when I logged in from my amdroid phone (after reset) the streak was reader to zero:-(
Same problem here; one of my languages was reset to zero, even though I earned points in both of them. Gamification is nice when done well, but when it's messed up, it really ruins the motivation.
My streak disappeared and I had coins for that day. No one ever explained it nor acknowledged it. So now I could care less about a streak. To me it is useless.