When moving a node and grey shadow suggest where it will be put, after release button and immediate quick move with mouse pointer to different place, can cause that the node is not placed to the shown grey area, but it is put back to initial state.
The issue also applies to the state, where a mouse pointer is above another node (which is not allowed). There is shown as grey area than red frame on not allowed node. After release button, the node is put back to the initial state.