Stryd uses Bluetooth to communicate with your phone, and also certain watches (e.g., Suunto or Polar). Stryd can only communicate with one Bluetooth device, phone or watch, at a time. If already connected, Stryd cannot be found by other Bluetooth devices. These are some scenarios most commonly causing Stryd not to be seen by the Stryd app:
Make sure Bluetooth is enabled on your phone!
Force quit the Stryd app, and toggle Bluetooth off/on and try again.
Your Stryd has been connected to another device, such as your Bluetooth watch, tablet, or second phone. To solve, disconnect Stryd from the other Bluetooth device. To ensure disconnection, power down all nearby Bluetooth devices.
Something else could be wrong. Restart your phone by powering it off and powering it back on. This is the best way to start anew.
Try to connect with your Stryd while it is on the charger.
If possible, use a phone of a family member or friend to install the Stryd app and connect to Stryd.
There is an app available to verify whether Bluetooth is working on your Stryd. These apps are intended for developers, but are a good way to determine whether the phone or Stryd is causing the problem. For iOS, there is LightBlue Explorer and for Android there is nRF Connect. Both apps allow you to scan for Bluetooth devices. If you Stryd is operational, it will show up in the list.
If you are using an Android phone, check the following:
Make sure in the Application Manager of your phone that the Stryd app has access to location.
Make sure location services are enabled.
Android versions 4.4.2 or older may not work.
Some Blackberry, and other uncommon phones may not work with Stryd.