Pretty sure I watched this on Netflix but can’t seem to remember the name.
Basically, this family moves into a rural house and learns that there is a mysterious creature (reminded me of the skin walker) that keeps showing up. The first encounter is in the woods when they see the creature, and have a run in with the neighbor who was on horseback and kind of a prick. Then these events keep happening in the house and their child (I believe a boy) keeps disappearing during these events, but always shows back up after awhile. They come to find a false wall in the house at the end of the movie that goes into a tunnel (this is how the kid was being taken), and this tunnel leads to what looks like an observation room. This is where the kid was being taken to every time he disappeared.
Fast forward to the end of the movie, the family moves out and you learn that the realtor is the one facilitating this whole operation and basically recruits families to buy this house to do the experiments on the children.