[BUG] Trackers are tracked normaly on out window, but one or more trackers in SteamVR disappears

[ju1ce]

When using the additional smoothing parameter, some users report one of the trackers are not seen in SteamVR, despite tracked perfectly in the out window.

Other notes:

• On the out window, the affected tracker still has the RGB axis following it, which indicate that other components of the system are working correctly: the tracker poses are being sent, regular smoothing on driver works, and the correct poses are reported back to ATT.
• The problem seems to be user dependent. Most users never report this problem, while for a few users, this happened every time.

Possible explanation: When using additional smoothing, the smoother combines the previous pose sent to steamvr with the pose predicted for current frame. This causes a problem where, if pose is NaN at any point in time, all future poses will be NaN as well, causing the tracker to disappear completely instead of disappearing for just one frame.

Workaround: Solution has not been found yet. If you encounter this issue, set additional smoothing to 0 and restart SteamVR/ATT.