Probably i fixed this problem changing the chunk render from 8 to 12, then the slimes showed themselves.
I created a world then i update to 1.8.1 pre3. And i having the same prooblems, no slimes at swamp ( problably because is not the right moon ) and no slimes chuncks at all.
I stil got the same problem in my singlepayer world. If i delete the end folder it will regen?
No way to respawn ender dragon, i tried 4 crystals. Im playing 1.10.2