beej
Moderator
The piezo senses physical vibrations - the transducer is in the saddle. So there needs to be enough pressure from the string on the saddle for it to work.
When you use the trem, occasionally the strings aren't in contact with the saddle and so the sound can cut out.
When you use the trem, occasionally the strings aren't in contact with the saddle and so the sound can cut out.