if this altered state makes you invisible and/or unreachable, or able to pass through solid objects, how come the ground/deck you stand on effectively stops you from drifting through the floor/ground?
Lots of TV shows and movies feature invisible men—where their matter is actually invisible, rather than cloaked by a Harry Potter-style covering—yet they are still able to see the world around them. If their atoms have been altered so that light passes right through, or does not interact normally... (The makers of the game QUAKE thought of that, which is why users of the "ring of shadows" were not totally invisible. Their eyes still showed, even in the game.)
As for partially shifted people passing through the floor, why should gravity still affect them? Or inertia? Perhaps a higher-tech visual effect could be created where the Defiant
side of the shift will "give" a little, like rubber—"smearing" a bit like paint as McCoy's hand passes through and "snapping back" afterwards.
For that matter (no pun intended), why should the suits the landing party was wearing not start shifting through their own bodies? If their own bodies no longer contacted themselves, the landing party would quickly turn to mush. (How's that for insanity-inducing pressure?)
Most fantasy does not bear close scrutiny. I remember watching a BATMAN episode as a kid, pointing out the silliness of something, like Bat Shark Repellent. (And the fact that our heroes just happened to have a can handy.) My brother laughed and said, "That's the only ridiculous thing you noticed?"