Here's an unlikely fix, but perhaps it could be your problem.

Have you changed the location you keep your phone while riding? I used Strava through my Android in my back jersey pockets and it was incredibly precise. Then one day I rode around my neighborhood a bit wearing basketball shorts with no pockets, so I just jammed the phone in the front of my waist band. Turns out that my body must have messed with the signal when I was hunched over riding, because the map (although very loosely correct) had me driving over houses when I checked it later. If I had to estimate, I'd say it was around 50 feet off just because of where I stored my phone while riding.