The interactables can be grabbed in 2 ways.
1) you get tracker to collide with them and grab (press and hold mouse 2 if using simulator) - that should pick up interactable
2) You pick them up with 'two thin lines' - each of this lines is
ForceGrabPointer ie in farm scene
/VRTK Prefabs//AvatarPointers//ForceGrabPointers/LeftGrabContainer those pointers will allow you to grab objects from distance depending on their setup.
In farm scene they'll trigger
Deactivate that means they'll stick to your hand when you release (mouse 2 in simulator) while aiming at
There is another setting that may be causing
ForceGrabPointer not to work for you - the prefab follows
/VRTK Prefabs//AvatarPointers//ForceGrabPointers/ValidityRule which specifies that layer of interactable needs to be
Water - by default when you drop
interactable prefab into the scene it has
And you cannot use pointer to grab
Change layer on intractable and it's children to
Water and you'll be able to grab