I've a Cateye Strata Cadence on my bike, and while I had noted an issue with the mileage before yesterday, I finally realized what the problem is. For some odd reason, it only adds distance/adds to the odometer when the bike is upside down! (I turn it over to clean the chain).

Yesterday I had it out and noted that while it picked up cadence fine, it wasn't picking up speed nor distance. It makes little sense to me that it won't pick it up when upright, but that it does when I have turn it over and am moving the crank by hand - at least the odometer moves...

I am trying to avoid a special trip to my LBS who installed it, though I will if I can't figure this out. Any idea what might be happening?