Repro Steps:
1. Open "SampleScene" in the "ReproParticleSystemScale.zip" project
2. Make sure that the properties on ParticleSystem GameObject are:
-Simulation Space -> World
-Scaling Mode -> Hierarchy
-Renderer > Render Alignment -> Local
3. Change ParticleSystem Start Size to 10 or more
4. Press Play on the ParticleSystem if it is not already playing
5. Try altering the x Scale on the Transform

Expected Behavior: The Individual particles are expanding by the number of times provided in the transform
Actual Behavior: The Individual particles are shrinking by the number of times provided in the transform

Reproducible with: 2018.3.0f2, 2019.1.0a14, 2019.2.0a1
Regression first introduced in 2018.3.0f1
Does not reproduce with: 2017.4.18f1, 2018.3.0b12, 2019.1.0a10

Note: The Emitter(shape) itself is actually expanding. Only individual particles have the issue.