OK well it looks like I made a silly mistake regarding this and have solved my own issue. No guarantee that others with this same or similar issue will have the same or similar solution, but I'll share it here anyway.
I saw in a thread with a similar problem where it was suggested to try making one of the other (failing) design points as "current" and going to the model to see what the issue is.
https://forum.ansys.com/forums/topic/parametric-study-error-in-ansys-workbench/
I tried this and, lo and behold, I saw that most of my components were missing. As it turns out, I had saved my assembly model with several components hidden, and I guess that reproprogated back into ansys as the components simply not existing. Once I unhid the components, saved the file, then went back to ansys and reran the design points, they all generated values no problemo.
TL:DR; design points didn't work, saw solidworks models were hidden, unhid them, design points working again.
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