my analysis vs. list-interpolate :: what's my problem?

Dearest forum members,

I've been working for weeks on the analysis of a percussion sound using SPEAR, but since I am interested in sustaining frames in between the transients, I am exporting 1TRC SDIF files to resynthesize sinusoidal models. I'm having no problems loading them into Max via the CNMAT objects, but...

Using the CNMAT spectral tutorials as a base, I'm trying to make simple, smooth interpolations between frames using the list-interpolate object. But whereas the tutorials' example SDIF files produce smooth transitions where partials fade in and out by amplitude (or widen by frequency scaling and then adjust by amplitude) my partials produce sweeps across the audio range during interpolation. Almost always the lower partials cross the higher ones as they nearly switch places, and often new partials begin at the low end of the audio range and then spread out across the audio range "taking their positions" in the new model. Nothing in between the two models sounds like either sound source.

Is there a problem with my understanding of list-interpolate or is it in the analysis or the SDIF file types?

My most sincere apologies if this is such a noob question that it makes your jaw drop or your brain hurt.

I'm happy to share the patches or the analyses I've been making to deal with it, but I trust they're enough like what you'd expect if you've worked through the tutorials or used SPEAR. Does this problem sound familiar to any of you? I'm doing my best to de-noise the analysis but it's a challenge. Although the sound source is percussive, I get the same "sweeping" effect during interpolation if I'm using my own analyses of woodwind instruments, in which it's easier to track partials (even for me).

Any advice or suggestions would be very much welcome! Many thanks for your time.