The same issue occurs with "Not Equals" operators on this pin type.
Workaround: Add "softclass" to the TypePromotionPinDenyList in the blueprint editor preferences.
Result: There is only a single "Equals" option available, which does not work
Expected: There are multiple options for "Equals", one of them being specific for soft actor types
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-146282 in the post.