I’m making an animated model of a lighter with opening cap. I made a single bone for the cap (and only cap’s vertices are attached to it) and a simple opening animation, and then exported it to fbx. But all I can see in windows’ previewer and engine is dangling cap, but no lighter itself. Something wrong with my export settings or with the way itself? Normals are ok
I would suggest you make two bones, and make sure that every vertex has weights to a bone. How engines respond to unweighted, armature-deformed vertices is not something for which there is a standard-- it’s just not how this is ever done. I am not sure that is the root 
of your problem, but it is the first thing I would recommend trying.
Hello. If either your cap or your lighter is parented to each other, this is known to cause odd armature behavior on exporter. Are you using Windows 10 3D Viewer by the way? It looks like you might be.
Thanks, adding a bone and weight to invisible parts solved the problem!
Adding weight to invisible part did the trick, but thanks for mentioning parenting problem, good to know.