Project Fails to Headlessly Build in Unity 5.6+ With Unity Assert

[Talarian]

VolumetricLightingBuildFail.zip

See attached assets folder.

1. Make a new project in Unity 5.6+ (tested in 5.6.1p4 and 5.6.2p3)
2. Drop the assets folder in
3. Close Unity
4. Run the batch script "sparkbuild_test.bat" contained in the folder (on Windows)

Expected: a successful build
Actual: Build sort of succeeds (files are correctly output), but Unity returns an error in post-processing. Logs are as follows:

Assertion failed on expression: 'ms_Instance != NULL'

(Filename: C:\buildslave\unity\build\Runtime/Network/PlayerCommunicator/ManagedProxy/GeneralConnectionManaged.cpp Line: 118)

I narrowed the issue down to code in Area and Tube Light classes. Didn't get any further than that before deciding to move on to a different product, but figured others may be interested in what the issue here is. Might be a bug in the Unity engine, but this is the only time I've seen this error. Note that the build succeeds when performed manually within the Editor, it only surfaces using Unity's batch mode.

Edit: Here's the Unity forum thread where I'm reporting the same bug to Unity https://forum.unity3d.com/threads/build-fails-with-error-player-export-failed-reason-3-errors.473944/#post-3150668

[aviv-jellybtn]

Hi,
did you manage to fix the issue?
Am getting the same error trying to build in headless mode.

`Assertion failed on expression: 'ms_Instance != NULL'

(Filename: C:\buildslave\unity\build\Runtime/Network/PlayerCommunicator/ManagedProxy/GeneralConnectionManaged.cpp Line: 118)

##unity-automation:{"messageType":"MemoryLeaks","allocatedMemory":3969264,"memoryLabels":[{"Default":1608},{"Permanent":20240},{"NewDelete":105856},{"Thread":544},{"Manager":2184},{"GfxDevice":6428},{"Physics":8},{"Serialization":12704},{"JobScheduler":136},{"GarbageCollector":1048576},{"BaseObject":16000},{"Renderer":224},{"Terrain":224},{"STL":1280},{"String":32478},{"DynamicArray":3228},{"Utility":-1048576},{"PoolAlloc":-224},{"ScriptManager":3280},{"Sprites":3742168},{"VR":12908},{"EditorGui":12},{"EditorUtility":544},{"AssetImporter":32},{"RestService":72},{"License":594},{"UnityConnect":6032},{"Collab":704}]}
debugger-agent: Unable to listen on 812
Finished: FAILURE`