TypeLoadException only when running using dotnet run, apps works fine from published artifacts

[Antaris]

I'm getting a TypeLoadException for one of my types defined in an assembly that is referenced transitively. My solution setup is as follows:

samples\SecurityWebSample\SecurityWebSample.csproj (netcoreapp2.0)
src\Fx.Security\Fx.Security.csproj (netstandard2.0)
src\Fx.Security.Abstractions\Fx.Security.Abstractions.csproj (netstandard2.0)
tests\Fx.Security.Tests\Fx.Security.Tests.csproj (netcoreapp2.0)

My Fx.Security library references one of my packages from an internal NuGet feed, Fx.Messaging.Abstractions, which contains my type MessageBuilder.
Fx.Messaging.Abstractions targets netstandard2.0 like all other projects.

My unit test project Fx.Security.Tests builds and executes tests fine (and they all pass too!)

BUT

When I run my ASP.NET Core project (SecurityWebSample) using dotnet run (or from Visual Studio 2017 [15.3 Preview 7.0]), it throws a TypeLoadException saying it can't load my type:

TypeLoadException: Could not load type 'Fx.Messaging.MessageBuilder' from assembly 'Fx.Messaging.Abstractions, Version=0.2.0.0, Culture=neutral, PublicKeyToken=91f42c97e4c34ea6'.

BUT

If I publish this app using dotnet publish and then run the app dotnet .\SecurityWebSample.dll, it all works fine.

I can't get any more information out of the exception (there is no InnerException set).

Any ideas on how I might go figuring this out?

[Antaris]

Additionally, I've completely cleared my packages caches, and confirmed that I am running .NET Core 2.0.0-preview2-006497

[Antaris]

Closing this out, as I had some stray build artifacts caused by simply coping the Web sample project from my Fx.Messaging solution to my Fx.Security solution. Nothing to see hear.