If it's like other devices, wyou'll see 5 segments when it's full. The 1st is one hour, and the 4 smaller ones, each additional 15 minutes.
It's no triggered by "no activity" but "not enough activity", with the large segment been 100 or more steps in an hour, so when fill, it's <200 steps in 2 hours.
To clear the move bar you have to clear all segments. So if it's just the first one, take 100 steps. All 5, 200 steps. And the key is take those steps without stopping.
Yes, It's different that fitbit.