efcore: Absolute path in OutputPath breaks Add-Migration

I created a netcoreapp2.0 project from VS template and changed the output path <OutputPath> to be an absolute path. I use this (along with other MSBuild properties) on my devbox to separate where my source lives and where my intermediate and output directories are. This is useful for me since I want Dropbox syncing my code by not my binaries.

Minimal repro .csproj file:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.0</TargetFramework>
    <OutputPath>D:\Dropbox\Programming\Repro\Repro\bin\$(Configuration)</OutputPath>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.1.0-preview2-final" />
  </ItemGroup>

</Project>

I have tried older versions of the Tools package. The Program.cs doesn’t even matter since it seems like Add-Migration can’t even find the output assembly.

VS version: 15.6.4 NuGet version: 4.6.1.5019