The bug 

A sculk sensor does not detect ice generating on a body of water.

I put a sculk sensor down at the bottom of a lake that was 3-1 blocks deep ice formed on the top of the lake and sculk sensor didn't react to ice forming on lake. It also occurred one block above the sculk sensor and it didn't react, I didn't catch it on video though. It should activate, it is replacing a block. When I place ice on where ice is generating it senses me placing ice. When it is within the same range it doesn't detect it generating. Click here, that is make me think this is a bug. It is replacing a block, it should activate.