1. Download my attached project "cubes.zip"
2. Notice several "CompuoundCube" GameObjects in the project (they all should have script component "Matrix To Transform" attached to them)
3. Turn on the Game View window and enter the play mode. Notice that CompuoundCube (2) Object's transform has changed
Expected result: When a transform has a negative scale component, the value of transform.localToWorldMatrix changes in Play Mode
Actual result: Even if a transform has a negative scale component, the value of transform.localToWorldMatrix doesn't change
Reproducible with: 2017.4.14f1, 2018.1.9f2, 2018.2.14f1, 2018.3.0b8, 2019.1.0a7
Notes: CompuoundCube (1) and CompuoundCube (3) do not have negative transform scale values. CompuoundCube (2) has a negative transform scale value. If you leave all the scale values CompuoundCube (2) positive this issue doesn't occur