How to reproduce:
1. Download and open attached project "Warboards"
2. Open scene "WarBoard" in Assets/_Scenes
3. Select any object in the Scene with Collider

Expected result: Collider does not show warning and is able to edit in the Inspector
Actual result: Collider shows warning and is uneditable in the Inspector

Reproduced with: 2018.2.0b8, 2018.2.5f1, 2018.3.0a10
Does not reproduce with: 2018.2.0b7

Notes: The issue persists when creating new Objects with Colliders in the Scene

Warning: "The module which implements this component type has been force excluded in player settings. This object will be removed in play mode and from any builds you make."
Version 2018.3 warning message: "The built-in package which implements this component type has been disabled in Package Manager. This object will be removed in play mode and from any builds you make"

Workaround: In Editor click Help/Reset packages to default