Deploying a wp8.1 app fails with:

Exception: Failed to build Visual Studio project. Output:

AssemblyConverter done.
NewUnityProject29 -> C:\Users\Vilius\Documents\New Unity Project 29\New folder\NewUnityProject29\bin\ARM\Master\Template.exe
C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v12.0\AppxPackage\Microsoft.AppXPackage.Targets(852,9): error MSB3819: Cannot find assembly "C:\Users\Vilius\Documents\New Unity Project 29\New folder\Players\WindowsPhone81\ARM\Master\BridgeInterface.dll", which may contain managed resources that need to be included in this app package.

To reproduce:
1. Build & run a new project for WP8.1
2. Notice the error in console

You can build, but deploying through visual studio will not work either. It fails with:

Error 1 Cannot find assembly "C:\Users\Vilius\Documents\New Unity Project 29\New folder\Players\WindowsPhone81\ARM\Debug\BridgeInterface.dll", which may contain managed resources that need to be included in this app package. Please ensure that this assembly exists.