Rotation of skeleton root node rotates the skeleton but not the skinned meshes

In the example there is a node with skeleton. The node is rotated around Y axis by 1 degree every 100ms. All the child Joint nodes and the light node are rotated together with the parent node but the Mesh nodes are not rotated.
The Mesh transforms become correct only when the root joint local rotation changes, which is done by a timer every 500ms.