The bug

In some cases, falling from a height may not produce any particles

How to reproduce

This method will probably require several tries.

1. Build or encounter a staircase, e.g. the roof of a village house
2. Fly up to a height that would definitely give way to falling particles
3. Start falling
4. Before you hit the ground, move forward in the downstairs direction

Expected results

Particles, always.

Actual results

Every so often, particles don't get generated.