VMTK centerline extraction trouble?

Operating system: Windows 10 (20H2)
Slicer version: 4.11.20210226
Expected behavior: Extraction of centerline within a model
Actual behavior: Centerline curve is not constrained to the model space

Hello all -

Wondering if anyone can help me troubleshoot extracting a centerline from a structure (in this case, a segmented spiral ganglion). I’m doing my best to follow along with some of the tutorial videos posted by PerkLab, but I am having some difficulties in extracting a centerline curve (see images hopefully attached). The centerline model seems to have been created successfully, but the curve itself only contains three control points and exceeds the bounds of the model - what steps can I take to constrain the curve inside my target model?

Any help in troubleshooting would be greatly appreciated!