Setting a parent and child static mesh scale to negative effects the rotation on child movement

Setting a parent and child static mesh scale to negative effects the rotation on child movement

This is a regression. Worked in 4.11.2.

User Description:

We have a simple project example (see attached) where we have a 4.11 project and two static meshes. One is a child of the other. They both have various changes to their scales and rotations. Now open this project in 4.12 preview 5 and you will find that the child mesh is rotated in a different way.

From test project

1. Open the attached test project
2. Select the SM_BoxText2 child in the World Outilner
3. In the Viewport, use the Translation widget to move the actor around

Results: The Z-Rotation value with flip between a positive and a negative value for each tick the child object is moved

Expected: For the rotation value to stay the same regardless of the negative Scale value

From scratch:

1. Open a new blank project
2. Import the attached test fbx
3. Drag an static mesh into the level
4. In the Details panel, set the Scale to 1.0, 1.0, 1.0 <--- note the Y field is minus one
5. Drag another static mesh into the level & make it a child of the first one
6. Set it's Scale to 1.0, 1.0, 1.0 <--- note the X field is minus one
7. Set it's Rotation to 0, 0, 110
8. Save all
9. Select the child static mesh and in the Viewport, use the Translation widget to move the actor around

Results: The Z-Rotation value with flip between a positive and a negative value each tick the child object is moved

Expected: For the rotation value to stay the same regardless of Scale value

Scene Graph resolves incorrectly with a project upgrade from 4.11 to 4.12