DEVICE: Samsung Galaxy Tab A
Guardians do not respawn in and around Ocean Mouments like they are supposed to. I noticed this when raiding a monument in MCPE.
STEPS TO REPRODUCE:
1. Use the seed: -1436927780
2. Go to the Ocean Monument that is in the ocean to the right.
3. Now use the /kill command to kill all of the guardians. /kill @e
4. None will respawn like they are supposed to.
EDIT: In the screen shot, I used commands to remove the blocks of the Ocean Monument. This is not required to test the bug however, I just did it after the fact to make sure there were none inside that I hadn't found.
EDIT: In 0.15.90.8, Ocean Monuments don't generate for some reason. So will have to wait until that is fixed to reconfirm.