Tampered contact sensor

Hi I recently purchased an additional 2nd gen contact sensor for a kitchen window. I installed the sensor and immediately received a tamper notification, and now I can’t get rid of it. I have tried/checked the following: - Reconfigured device - Removed device and re-added - Checked for the “click” when sliding the sensor back on its mounting plate - Checked that the sensor is stable, not moving and feels secure - Checked that the sensor has ample signal - it’s in range of both the base station and range extender (there are sensors further away that work fine too) The sensor obviously works because when I open the window, it does it’s job. Is there any way of removing this tamper notification? My system is all 2nd gen. Thanks Ben