Unfreezable with large dataset

[Camsbury]

I'm succeeding in joining smaller chunks of a large dataset in memory (that have been frozen/saved individually), but when I concat them and try

  (tio/put-nippy!
   (tio/gzip-output-stream! path)
   (tds/dataset->data ds))

I get something like the following. Have also seen I here instead of J. Maybe some compression stuff gone awry?

Unhandled clojure.lang.ExceptionInfo
   Unfreezable type: class [J
   {:type [J, :as-str "#object[\"[J\" 0x7fbe02ac \"[J@7fbe02ac\"]"}