Textures imported from package don't show the right thumbnail in project view
Regression in 2017.1+

1. What happened
Importing textures from and external package don't have the right thumbnail in project view

2. How we can reproduce it using the example you attached
- Load the attached project
- The content reflects the results of importing the fbx model in the project (Materials and .fbm folder created and populated)
- Browse to the .fbm folder and look at the thumbnail for Normal maps. (all the textures thumbnail are correct matching what appears in preview windows)
- Delete the .fbm folder
- Browse to the ExportPackage folder and double click on the mike_textures package. (this package has been created right from the current project by only selecting the textures to be part of the package)
- From the import package dialog, check all the items and click import
- Browse to the .fbm folder again and see the thumbnail of the normal maps, they use a thumbnail from another texture, the preview window display is correct though