Weird spec problem

weird.clj

(defn- dependency-indices
  [length]
  (s/tuple (s/int-in 0 length)
           (s/int-in 0 length)))

(defn- index-set
  [length]
  (s/gen (s/coll-of (dependency-indices length)
                   :kind set?
                   :max-count (/ length 2))))

(s/def ::tasks
  (s/spec (s/coll-of ::task)
          :gen (fn []
                 (gen/bind
                   (s/gen (s/coll-of ::task :min-count 5))
                   (fn [tasks]
                      ;; If we remove the gen/tuple - just make it (gen/return tasks), it runs
                      ;; fast.  With the gen/tuple, it says "Couldn't satisfy such-that" consisitently
                     (gen/tuple (gen/return tasks)))))))

(s/def ::task (s/keys :req [:task.def2/uuid
                            :task.def2/name]))

(s/def :task.def2/uuid uuid?)
(s/def :task.def2/name (s/and string? not-empty))