Cylinder, modelled M10 thread, then Shell on an end face: Shell fails because the faceted thread leaves the body as triangles, not a valid solid, so fillets and booleans downstream fail too. The reporter argues the 'temporary' faceted cut will harden into a ceiling.
From the Grok pain-radar digests, Oct 28-29 2026 (Oct 28 8:41 AM ET through Oct 29 early-morning Haitch editions). Verified live 2026-10-29: issue/PR read; title and state confirmed.