Spawners from v0.11.1 problem

After I place a zombie spawner in 0.11.1 and updated to v0.12.1, the zombie spawners disappear, but the flames are still there and the mobs are still spawning.

Steps to re-create scenario:
1)Download MCPE v0.11.1
2)In creative, place some zombie spawners down.
3)Update to v0.12.1
4)Go into the world, and the zombie spawners have disappeared, leaving only the flames and the zombie figure.

NOTE*
Even if you place a block on it, it will still be there.

P.S.
This might be a duplicate of MCPE-9121