I had to replace a Pixie and cannot add a sensor to the area of garden it irrigates. The Timer->Settings->Sensor contains no add button.    Android 12 on a Samsung S21, App version 3.0.1

What am I missing? 

Just booted a pair of Pixies for the coming grow season having recharged the packs via USB.  One unit is fine, the other booted one then shutdown and is dead.  I swapped the batteries around and the problem followed the the battery.   I don't see a replacement battery pack on the store so how do I get this replaced?   Pixies got bought last year.