After computer and OS upgrade, have to mark incoming spam manually

Recently migrated to a new M2 MacBook Air with Sonoma (previous Air and OS were old). Ctrl-S does identify spam and move it to Junk, but I have to select items manually. What setting am I missing for this to be automated? (The old Mail rule is turned off, per instructions.)

Please see Quick Start to Keep SpamSieve Working With Apple Mail When Updating to macOS 14 Sonoma.