when day night cycle is false, daylight sensor updates in a strange way. 

Execute command /time set 1, then the daylight sensor never updates its signal, even if the light turns darker or brighter (e.g. putting or destroying some opaque blocks above it). unless you click it to invert it.

Execute command /time set 20, then the daylight sensor updates its signal every game tick.

As long as the time is a multiple of 20, the daylight sensor updates every gametick. Otherwise, it never updates.

In java edition, daylight detector updates every 20 gametick, But in the bedrock edition, it depends on daytime, instead of gametime, which doesn't make any sense.