Easy to reproduce:
- Create an empty Unity (2018.1.0b13) project and open “Edit” =>> “Project Settings” =>> “Player” menu
- Set “Scripting Runtime Version” to “Stable (.NET 4.x Equivalent)”
- Restart Unity
- Drag a mesh into the scene (cube or anything)
- Open animation editor (“Window” =>> “Animation”)
- Click “Create” animation clip button
- Animate something with a negative rotation value. Unity will not accept the entered value and overrides it with some other weird number. You can see this as soon as you preview your animation.
Case number: 1027800