Why isn't my S Health pedometer counting?

[AC Question]

S Health pedometer stops counting

I recently got a Galaxy S5 and turned on the S Health pedometer. I love the convenience of this app, but I've noticed that the pedometer will abruptly stop counting steps for long periods, multiple times a day. When I've searched for this issue, I haven't seen other people posting this complaint, so I wonder if it's unique to my particular app or device.

 

[Zebaya]

Same problem. Only had the phone for a few weeks, it stopped counting a few days ago and nothing I do will get it to start again.