To reproduce:

1. Download attached project "2018.2.12f1.zip" and open in Unity
2. Download "UnityPivotbox.fbx" and drag it to the Project view
3. Drag "UnityPivotbox.fbx" to the Hierarchy
4. Observe on which position is Mesh and its Pivot
5. Right click on "UnityPivotbox.fbx" and press Reimport

Expected results: Mesh and its Pivot remains in the same position
Actual results: Mesh moves to another position and its Pivot resets to Zero

Notes:
- This issue appears on both Windows and macOS but is slightly different - on macOS Mesh moves to another position with its Pivot
- This issue reproduces only with Models without Animations
- This issue happens when Code which is bellow is executed twice:

"public class ImporterModel : AssetPostprocessor
{
void OnPreprocessAnimation()
{
var modelImporter = assetImporter as ModelImporter;
modelImporter.resampleCurves = false;
}
}"

- Without above-mentioned code, everything works fine

Reproduced on Unity 2017.3.0a1, 2017.4.17f1, 2018.1.9f2, 2018.2.19f1, 2018.3.0f1 and 2019.1.0a11