After the build, the object is no longer a childs of another objects

There are 3 chairs in the game that move up and down with an animation. People are sitting on them and they are the child objects of chairs, so they move up and down with them. People are not static, they have their own hand movement animations and it works. So, after the build, people hang in the air and don't move up and down, and their own animations and animation of the movement of the chairs are works fine. I can see it only in the build. When I launch the game in the engine, there is no such error. Looks like buid version of the game don't see, that people are childs of the chairs. Why this can it be? P.S. Recently updated engine to the latest version