Small part will not slice or print (UpStudio 2)

Hi all. Odd and annoying problem. Everything is working fine, UpBox+, UpStudio2 ( has been reliably churning out parts. But…I tried to print a small part, a hex ring about 1/2" across, a part I have printed before with no problem, but now the part will not slice, and causes UpStudio to crash…! If I increase the part size 3x, it will slice correctly, but that’s not a solution, as the bigger part doesn’t fit of course. I tried mounting several of the parts on a flat plate, and in preview mode, the plate slices, but the parts disappear…!! I’ve redrawn the part from scratch, still no go. Frustrating. Any suggestions?