LinqKit PredicateBuilder returns all or non rows

The And extension-method does not modify the original predicate - it returns a new predicate representing the original predicate ANDed together with the specified predicate.

Effectively, your operations are not changing the predicate referred to by your pre variable, meaning you end up with either all or none of the records based on whether you initialized the original predicate to true or false.

Try:

    var pre = PredicateBuilder.True<MyEntity>();
    pre = pre.And(m => m.IsActive);

If you are planning toOR predicates together, remember to start off with a false initial predicate.

    var pre = PredicateBuilder.False<MyEntity>();
    pre = pre.Or(m => m.IsActive);