My slime farm wont spawn anything. I built it all in survival in a slime chunk and followed a YouTube tutorial but slimes just don't spawn at all. I went afk for an hour and still nothing. So I went into creative to figure out whats wrong, cloned it into a swamp biome and it worked. I guess slimes only spawn in swamps now and slime chunks are irrelevant? Anyway, after that, I modified the farm to be a general mob farm but still absolutely no spawns occurred. I'm so confused?? Anyone able to help out? Here's the details:

Seed: 1530009084
Broken Slime Chunk: from 1168, -752 to 1183, -737
Slime Farm Tutorial: https://www.youtube.com/watch?v=K9_xrbFYrZs