Visual Studio 2017 and .Net Core project.

Model explorer nodes collapse every time you navigate to another document and go back to Entity Developer designer. To reproduce the issue:

1. Open an .efml file
2. Make sure database model explorer is visible.
3. Expand any nodes (Methods, Complex Types, etc.)
4. Open another document (let's say some C# code)
5. Go back to Entity Developer.
6. Observe that all nodes are collapsed.

This issue results in less productivity and frustration when you need to go back and forth between code and DB model.