edit: seems to be resolved as of 1.11.3; crosschecked a number of slime chunks. all are back in working order.

slime chunks are no longer spawning slimes. it seems to be an issue for some but not all.
https://www.minecraftforum.net/forums/minecraft/discussion/2961542-slime-chunks
i had checked a known slime chunk from an earlier save and found it to be out of order. so i loaded a new game and built a slime spawn column centered on coords 1384, ~, -8. that should be the center of a slime chunk but my column yielded  no slime spawns after waiting for about 10 minutes at an appropriate  distance.
seed used was -1801362067

edit: got some consensus on the forum, apparently dosnt affect windows 10 pc edition.