How to reproduce:
1. Open the attached project
2. Switch to Android platform
3. Make sure that Scripting Backend is set to IL2CPP
4. Build and Run on Android device in Player Settings
Result: Build fails with errors:

Error1:
IL2CPP error for method 'System.Void UnityEngine.UI.ObjectPool`1::Release(T)' in assembly 'C:\Users\ievar\Downloads\case_867606-AndroidAvatar (1)\Temp\StagingArea\assets\bin\Data\Managed\UnityEngine.UI.dll'
Additional information: Build a development build for more information. Sequence contains no matching element
Error2:
Failed running C:\Program Files\Unity 5.5.0p3\Editor\Data\il2cpp/build/il2cpp.exe --convert-to-cpp --emit-null-checks --enable-array-bounds-check --compile-cpp --libil2cpp-static --platform="Android" --...
Error3:
Exception: C:\Program Files\Unity 5.5.0p3\Editor\Data\il2cpp/build/il2cpp.exe did not run properly!
UnityEditorInternal.Runner.RunManagedProgram (System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, System.Action`1 setupStartInfo) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/BuildUtils.cs:98)

Note:
Try building on iOS device, it will fail and you will get compilation errors
Try building on WebGL , it will fail and you will get compilation errors
Compilation errors seems to be related to Bass.Net.Android DLL which targets .NET 4.x

Reproducible: 5.5.0b8, 5.5.0p3, 5.6.0b3
I can not check if this issue is reproducible in Unity 5.4, because Unity is not forward compatible.
If this issue is related to 811997 then it is reproducible in 5.3.7p3 and 5.4.4f1