Married Sims Declared Siblings via Family Tree

After the most recent (3 Feb) update, I opened my game to see that my main sim and his (very late) husband are now designated as brothers on the family tree. I cannot change this relationship in any way. When I reverted to a save from 2017, when the husband was still alive, they were still listed as brothers in the family tree and even with testing cheats on/full edit mode in CAS, with all mods removed, I cannot render them unrelated spouses again.