Shulkers don't react to lava when they are being attacked by lava.
MCPE-18313
Shulkers don't teleport when they are in water/lava
Resolved
Fixed
2
(Unassigned)
43879, 57650
Confirmed
Tablet - Android - Other (Specify in description)
Android 5.0
lava, shulker, water
0.17.0.1, 1.0.0.1, 1.0.3, 1.0.4.0, 1.0.4.1, 1.0.6.0, 1.0.5.54
1.1.0.9
Retrieved
Fixed in 1.1.0.9 - there are still a couple of related issues, reported at MCPE-22087 and MCPE-22088.