Cook, stirring occasionally, until vegetables are mostly softened, about 5 minutes. Add flour and cook 1-2 more minutes.
Add chicken broth, corn, thyme, and bay leaves to the pot. Bring to a boil, then reduce heat and simmer until potatoes are tender, about 15-20 minutes.
Stir in heavy cream, sour cream, and crabmeat. Cook until heated through, about 5 minutes.