We just want you to know that your horse ride is private to you and used for the sole purpose of you recording your rides with your horse. We don't use this data in any way.
You're probably using an Apple device. Apple has put in some new privacy features that restricts the reporting of location data for about 200 yards/meters. After that, it starts notifing apps you have given permission to. Just stick the phone in your pocket and enjoy the ride. We'll capture whatever Apples wishes to provide. :o)
3rd party apps like ours are not given the same information that Google and Apple are given. That is okay, but when you see those spike lines, that is just your device trying to tap into location helpers like local wifi and cellular towers.
After testing this for over a thousand miles, I found having the phone in a semi-vertical position is best. So on the side of your pant legs or one of those arm straps where you can have your phone on the side of your arm like runnings have.