There's more to it than merely moving out of sight behind some kind of concealment. What happens happened to me but it was so dark that I couldn't see that I couldn't see. The mechanism is infrasound ... abnormal but absolutely not paranormal. Not merely used by elephants, tigers, etc, but predicted to occur in human males at about the 8 foot range if the vocal tract extends proportionally with height (it doesn't quite). Sound is waves. Powerful waves do not stop at obstacles, they vibrate the obstacles unless the obstacle is "rubbery" enough to absorb the wave energy without transmitting it. Sound absolutely will move fluids. I've talked to witnesses who had their "events" in daylight so they could see and describe the effects. What's happening, based on the evidence, is the infrasound waves vibrate the fluids in the eyeballs and the larger eyeward end of the optic nerve creating a temporary effect much akin to macular degeneration ... a situation where the witness can see around the periphery of their vision but not in the center. My research partner reports having precisely that happen ... she "knew" there was a bigfoot in front of her but couldn't see it. When she looked aside she could see a generally very large human-ish shape, but if she looked back towards it, either just her eyes or her whole head, it disappeared into a general blur ... in other words, she coudn't see what was behind it either.
Like I said, the bigfoot doesn't vanish, doesn't disappear, doesn't go anywhere, doesn't "cloak", it just messes with our vision so we can't see it if we look towards it.
The reason people won't look at this is fear. It's a thing we're absolutely unable to counter. People simply do not know how to be that afraid so they deny it is possible. It's part of "can't happen to me."
MIB