The Bug:

When I activate a lever placed on a full block, it activates the trapdoor, but when I activate a lever placed on a stair, it doesn't activate the trapdoor. The two screenshots I attached below show the behaviour.

How to reproduce:

Place a Lever on a Stair, then place a Trapdoor anywhere on the same Stair, and then activate the Lever.

Observed Behaviour:

Lever can't activate nearby Trapdoors when the Lever is placed on a Stair.

Expected Behaviour:

Levers can activate nearby Trapdoors when the Lever is placed on a Stair.