Don’t think it’s the manifest file itself (though I guess the *.json files are now required?).
The crash happens despite the .json file being where it is passed into the SetActionManifestPath - but of course the vr::VRInput() call already returns the nullptr, so it doesn’t even reach that function. As far as I can tell, the vr::VRInput() errors out in the call to VR_GetGenericInterface with error VRInitError_Init_NotInitialized. That’s as far as I got with debugging so far…