An user of my app reports the next
I found out that when I put my phone on charger (via fm transmitter USB port) then the problem exist. If I run the phone from battery, then the GPS in the app works fine. (can get coordinates, speed, address without issues)
I checked the video he sent and yes speed during driving was 0, only once it was updated in 1 minute
He reports that some other apps which use GPS as well work fine in such case. He showed that on video too, that other apps work fine.
So without connecting device to that transmitter, GPS in my app works fine for that user.
What could be a problem?
Found the issue:
When a phone is connected to that FM transmitter via USB then GPS accuracy (error) becomes very bad, from 40 meters and higher.
My app ignores new GPS locations with accuracy higher than 20 meters, that's why other apps were working for that user.