We are facing the same issues. I was able to narrow it down substantially, though.
The issue seems to occur, whenever the vive controllers get sent to power-save/turn off when idle…
When you turn them back on, Unreal seems to wrongly handle SOME internal indices…
You will get your controller back as usable controllers, but the tracker will also become some sort of controller (we assign meshes to found controllers and the tracker gets assigned a controller mesh whenever that issue happens as well)
The orientation of a tracker and a controller seem to be different (internally), so the axis orientation are not working anymore…and the forward vector is not what you’d expect it…
The only workaround to fix this, for us for now, is to repair the tracker with the system.
It’s a real issue for us though and it would be great, if someone could tell us more about it/have an in-depth look into the code…