Your system information

• Steam client version (build number or date): 1488992261
• Distribution (e.g. Ubuntu): Gentoo
• Graphics driver version (run nvidia-settings): 375.27.13
• Gist for SteamVR System Information: https://gist.github.com/valentindavid/64b4ee1ebdca82af92cdf6d4f0bedb10
• Opted into Steam client beta?: Yes
• Opted into SteamVR beta?: Yes
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

GetControllerState from FnTable:IVRSystem_015 (C API) always return with a zeroed VRControllerState_t struct when GetControllerState from IVRSystem_015 returns with a correct VRControllerState_t struct.

This is a problem for ViveCraft for example that uses the C API through JOpenVR. No button on the controllers work.

Here is an example of program. When running, hold buttons. It should then show non zero values. But it is always 0.

#include <openvr.h>
#include <openvr_capi.h>
#include <iostream>
#include <chrono>
#include <thread>

int main() {
  vr::HmdError err;
  auto ignored = vr::VR_Init(&err, vr::VRApplication_Scene);

  auto vrsystem = (VR_IVRSystem_FnTable*)vr::VR_GetGenericInterface("FnTable:IVRSystem_015", &err);

  if (err) {
    std::cerr << vr::VR_GetVRInitErrorAsSymbol(err) << "\n";
    return 1;
  }
  while (true) {
    for (vr::TrackedDeviceIndex_t i = 0; i < vr::k_unMaxTrackedDeviceCount; ++i) {
      VRControllerState_t state;
      if (vrsystem->GetControllerState(i, &state, sizeof(state))) {
	std::cerr << state.ulButtonPressed << "\n";
      }
    }
    std::this_thread::sleep_for(std::chrono::seconds(1));
  }
  return 0;
}