If your Strap Edge is connected through Bluetooth, make sure it is connected to Woojer Strap Edge Stereo and not to Woojer Hands-Free.

Also: Since Woojer Edge is driven by sophisticated software, this may be caused by a software "glitch". It can happen for example when switching the audio source from Bluetooth to 3.5mm. If you're experiencing such behavior, you should hard-reset your device. Please refer to the following article for more details.