I play on a realms server that is managed by someone who doesn't play very much and I've had to quit Minecraft completely. Hours upon hours of work have been ruined due to creepers and zombies spawning on top of well-lit areas and ruining my work or killing my villagers. Really hoping this is fixed ASAP.
One of many images of my broken world.
Something I just remembered- hope this is seen by a developer. I was actually traveling back and forth from the nether (which as you might know loads extremely slow) but also the first time I enter the nether each session my game will crash and boot me out of my realm without fail. I remember specifically one time as I zoned back into my world through the nether portal in my picture above, all the lighting was broken - about 2 minutes after seeing it all working.
Hope this helps, happy to provide more info.