This affects our map on the realm as well as in single player on XBOX, Android, and PC version 1.4.2.0 as well as PC running with experimental gameplay.

Old slime chunks that used to spawn slimes no longer do and after cutting out 3 new slime chunks no slime's ever spawn.  It also seems like regular mobs spawn in these locations even when very well lit.

Seed -1104065594 Spawn chunk locations;

295, 36,233

281, 36, 216,

296, 36, 196