I've got a vehicle with a propeller that is suffering the "VY node not found" error. The issue is that, while I know why this happens normally, the jbeam of the propeller is already fully three-dimensional. Other than making the propeller more broad, I'm unsure as to how to make the current design function with the flexbody system. And although I can create a ring of extra nodes to support the flexbody, the propeller spins too fast for the extra ring to be stable; it shakes itself to pieces in seconds.
That's kinda clever, actually. For now, I've just placed an extra node ring in an area that isn't too unstable, though it's hardly perfect. So, I guess this is solved?
It depends on the 3d model. Vertices are connected to the nodes nearby, and if the vertices between these models are in different places, it may not be possible to connect the nodes and vertices. Having a 3d web of nodes is not always enough. For example, on my snowman prop I have a broom part. That broom has a base with 8 nodes, and with those nodes only it works fine. If I add a top node for the handle, VY node error pops up. Why? Because the top has 6 vertices and only one node. The lower nodes a too far away from the top to play a role. I "fixed" this by adding 2 more nodes for the top. So in your case, check if the other model has vertices in places where there are no nodes close by/not enough nodes.