If you have a clip defined by three node ids and you attempt to use the interactive mode (which makes no sense for the three-node option), the interactive movement of the clip will occur according to the plane tool, but will go back to the three-node representation when you release the mouse button.

Use clipping planes to create planar clips through arbitrary meshes. If you have a structured mesh (such as those in PLOT3D format), you may wish to use IJK clips instead. An IJK clip displays a plane of constant I, J, or K. An interactive IJK clip will sweep through the range of (for example) I displaying the JK plane at each I value. See Create IJK Clips for more information.