Intel (R) Core™ i7-6700K CPU @ 4.00GHz, 32 GB, NVIDIA GeForce RTX 2080 SUPER
particleorientationbug.rbxl (55.2 KB)
If you create a ParticleEmitter with the Orientation property set to VelocityPerpendicular, setting the speed to 0 will cause nothing to ever render, even with acceleration.
In this picture, there are 3 ParticleEmitters all with VelocityPerpendicular orientation, so the particles should face upwards
The left has only speed, the middle has only upward acceleration, and the right has both. Notice how no particles are visible on the middle emitter.
When a particle emitter has acceleration but no speed, the particles should still be visible.