Slime spawns incredibly limited/impossible

Slimes do not spawn as they should on Bedrock Edition. I have dug out two chunks at levels 5-15 (three platforms) using the slime chunk finder website. My seed is 3198785, and I have been using the chunks at coords: 2864, 368 - 2896, 352. I have afk'd 30 blocks away (allowing slimes to spawn but not despawn) for at least a few hours but not a single slime has spawned in these chunks the entire time I have been there. This suggests a big issue in the spawn rates.