I had a streak going of about 27 or 29 days I believe and I had bought the streak freeze before and still lost it after no activity yesterday. The streak was still present this morning but after i purchased another streak freeze to be on the safe side that's when it went back to 0.
The streak does not automatically update on your screen. I usually have to reload my home page before it shows the current value. Perhaps you had lost your streak but it was still showing on your screen.