Incessantly undercounts steps

The story is fun and the voice work is great, but the iPhone version of the app always dramatically undercounts my steps, so it really isnt useful for use as a run tracker. I will specify that I always run on a treadmill. I am unsure if this issue would occur were I running outdoors. Still, I am tried every single troubleshooting suggestion I can find online and none have made a difference.

CudLife85 about ZRX: Zombies Run + Marvel Move, v5.0.3