Steps to reproduce:
1. Open attached project(link in the description) OR download holo-toolkit project https://github.com/Microsoft/HoloToolkit-Unity
2. Open build settings and switch platform to WSA Universal 10 SDK
3. Open player settings and select IL2CPP scripting backend
4. Build for WSA Universal 10
build fails with errors as expected
5. Open player settings and select .NET scripting backend
4. Build for WSA Universal 10

Expected result: build succeeds
Actual result: build fails with errors as if it was built with il2cpp scripting backend

Workaround: create a new c# script to trigger recompilation

Reproducible with: 5.5.2f1, 5.6.0p1, 2017.1.0b1