I have been walking the same route for a couple of years now but over the past 12 months I noticed that the occasional step count was way under what it should be. This has continued to worsen so that almost every session is now wrong. For a 7km walk the count used to be over 9000 steps. Nowadays it is around 3100-3400 steps with the lowest reading of 2600 steps recorded a few weeks ago. Any ideas?