Bat spawner not working

Was the light level around the spawner four (night) or less?

Confirmed on Samsung Galaxy S4 Android 5.0.1 running MCPE 0.11.0 build 10

I tested it in creative mode, max difficulty, zero light level and could not spawn bats. The spawner was located on the ground in a room that was 7x7x4 (i.e. the spawner was in the center with 3 blocks space in all directions.

I can just see a little bat spinning inside the spawner when I placed the egg in there, but none spawn. I played with the light level and with recreating the spawner with different starting light levels. Still no luck.

I replaced the spawner with a skeleton spawner and it worked fine.

Thank you for the clarification, Russell. Were you below layer 63?

Doh. No I was not. I created a new creative world and dug down maybe 10-15 blocks. I'll test again shortly.

Yes, bat spawners work below level 63. I created a new creative world, found a cave that took me down at least past level 63 and created a bat spawner which worked just fine.