When toggled/enabled the 'noseInterstage' node is incorrectly positioned. Should be positioned at the top lip of the top tank/bottom of the top adapter, at the same place the upper fairing starts.

Is correctly placed after diameter/etc change. How to pass correct node placement to selectable node module?

Potential fix -- add updateAttachNodes(false); to the end of the Start() code. This should force-update the node positions even when disabled, but ensures that the SSTUSelectableNode module(s) have already started up and are initialized (prior to that point, e.g. during OnStart() it is not guaranteed that the other modules are present or have had their OnLoad() already called, especially if they are defined later in the part config than the parent/calling module).