SteamVR Controllers Not Working in Build, Works in Editor

I'm trying to build a Unity app using SteamVR that is working fine in the editor, but when I run the stand-alone version built for Windows x64, there appear to be some issues, such as controllers not appearing and behaviours not running.

In this case, I've got a single scene in Unity 5.5.3f1 (SteamVR didn't work in the latest 5.6) with the 'Player' prefab used so that I can take advantage of the interaction system.

In the editor, everything works exactly as expected. The scripts on the objects under the SteamVRObjects object run, the controllers track etc.

When I run the Windows build though, the debug lines I've got in the assets inside SteamVRObjects don't appear to run at all (ie. they've been disabled before they get a chance to Start, although their OnDisabled isn't called either), and the controllers don't seem to be tracking (or are off-screen). However, the VR headset itself tracks.

Note that I did try the SteamVR_Update_Poses trick to get it working in 5.6, but had no luck.

Has anyone found similar issues? Is there a workaround I can use? Do I need to use any other scripts other than the Player prefab?