Mobs no longer see buttons as full blocks in Bedrock Beta 1.16.100.55. This is likely due to improvements to mob pathfinding. Here's a video I made demonstrating the bug: https://www.youtube.com/watch?v=3Ek140awEaA

Existing mob farm designs rely on buttons to improve the efficiency of drop shafts, and this no longer works in the Beta. This a behavior that has existed in the game for years.

Player Expectation: Mobs see a button placed on the side of a block as a full block and pathfind over it, falling into a gap.

Game Behavior: Mobs avoid pathfinding onto buttons placed on the side of a block.

Consequences: Players spend days or weeks building multi-layered mob farms in their worlds and depend on the button mechanic to make these farms work. In the beta, these farms no longer work and players will not know why.

Suggested Change: Mobs should treat buttons placed on the side of a block as full blocks when pathfinding.

Precedence: The impact of this bug is similar to previous changes to slime chunk locations and pressure plates that were reverted because they broke existing farms.