The answer is “maby”. There are currently issues with native encryption, see my comment here: What's the common setup for ZFS encrypted home server - #11 by Log
I have absolutely no idea how to work through if your running into one of those bugs, or something else. My gut feeling is to suspect something else, not that that’s very helpful.
If you haven’t already, consider hitting up the zfs mailing list. There’s a nice official frontend for it here: Topicbox