If BreatheSync cannot pick up your heart beat for over 3 seconds it displays a cross on the heart symbol top right. This is usually because your finger positioning is incorrect. Please check the end of your left index finger is placed over the camera lens and the flash. Sometimes this can also be due to a lack of blood supply in your finger because your hands are cold - in this case warm them up! If you do not place your finger correctly a pop-up will show with this handy checklist –
Oops! Check your finger is …
✓ … on the camera lens
✓ … held steady - wait before adjusting
✓ … warm and dry
✓ … kept on the camera for the whole session
NB: This can also happen if you forget to give Breathe Sync access to the camera when the app first launched. To ensure this is correct go to Settings on your iPhone, then Privacy, then Camera and turn on access for BreatheSync.