Incorrect step count when running since IOS 13.3 update

[Deerrun]

I have had a Charge 2 for 2 years and it’s always recorded my runs fairly accurately.
However since I bought a new iPhone on 31.12.19 and updated to IOS 13.3 it’s not.

A 3 mile run use to be about 5330 steps but since the update it records a 3 mile run as around 4214 - 4328 steps and today it tells me I ran 3.19 miles yet it was only 3925 steps.

Also, I ran EXACTLY the same route on two consecutive runs yet the first one said it was 3.06 miles (4328 steps) and the second time it said it was 3.57 miles (4689 steps).

Consequently my average pace has increased from approximately 10’00” - 10’30” to 7’30” - 8’30” for a 3 mile run which is impressive but totally inaccurate!

I have not altered anything in my Fitbit settings.

This is rather frustrating. Is this a problem with GPS or stride length or step count??

[AlvaroFitbit]

@Deerrun Welcome! It's great to see you around! 

Let me help you with your distance calculation. Lets start by refreshing the link between your phone and your tracker to help improve the GPS signal reception:

• Go to your phone's bluetooth settings and remove all devices listed there.
• Restart your phone and restart your device. 
• Check that no battery saving app/feature on your phone is affecting your Fitbit app.
• Also, if you are using an Android device, check that your app has the necessary permissions (settings > apps > Fitbit > permissions) and make sure bluetooth and location services (GPS) are on. 
• You can find troubleshooting instructions here.

After this try measuring your stride length and enter it on your account to help improve the distance calculation.

Let me know how it goes.