Thanks for replying. Unfortunately, I tried that by copying the entire VRTK SDK Manager from one of the example projects, and I still got the same errors with Oculus SDK. I have to disable both the VRTK_InteractGrab and VRTK_Straight Pointer Renderer scripts on the controllers to get rid of the error (which of course disables my teleport and grabbing abilities).
I did notice for the VRTK Interact Grab script, if I create a dummy (cube) object under my 'hand' with a rigid body on it and drag it into the 'Controller Attach Point' field of the VRTK_INteract Grab Inspector, then that null error goes away, however, my ability to grab is a bit mucked up, and doesn't work very well (at least compared to when I left that field blank previously with the OpenVR SDK).
Anything else I can try?