I ran in the same problem. I removed the ZFS repo of ZFS itself. I
installed the Fedora version, after that the ZFS pool was unable to
be mounted (something with dependencies of features).
I then proceeded to remove everything of ZFS on my system and
installed again the ZFS repository. This turned out to be the
winning move. Why? I don't know, but the ZFS packages of the
repository compiles something. So, my bet it does something to the
kernel and with the upgrade of Fedora 23 it got broken.