"UV Values in outer cage that do not belong to the template"

I’ve hit an error while uploading my first sweater item to the catalogue. I’ve been trying to troubleshoot it for the past couple hours, and keep hitting dead ends. I’ve tried checking the UVs of the mesh, making sure the inner cage is inside the outer cage, making sure the outer cage doesn’t intersect, and I know I haven’t touched the UVs of either cage. The number 104 didn’t change while I did any of those things. I would love some ideas of where to look, or know if I should just give up and reimport a fresh template cage.

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