I was unable to reproduce your problem in NX 11.0.2 (or NX 12.0.2). I wonder if you have a delayed update set somewhere? What happens if you use the "Update for External Change" command after you've made the spline associative?
Hi @BenBroad Thank you!
It's a surprise to know you can't reproduce the problem. I just tried "Update for External Change", and the ghost non-timestamp spline persisted. I also checked "Update Model" button and found it unavailable.
The ghost non-timestamp spline is different from a common one: double-clicking it opens "Edit Object Display", but not "Studio Spline" dialog box.
I just found a way to let the ghost spline go: RMB > Unpack. This seems to be a workable remedy.