i was looking to slimes but i not found them in any swamps bioms i tried, i created a base in swamp biome and waited for 3 minecraft days and slimes not spawned there 
i puted my world seed in slimechunk finder and i create a room as large as
a chunk with torches for other mobs and i left from there in 20 blocks away after few minutes a slime spawned in slimechunk but after first time any slimes not spawned, after first time i tried on the same map in new chunks(slime chunks) but the same things happend , i tried in 1.16.5 version of the game with same that way but this did not happen and this system worked correctly by the way in 1.17.1 i started a flat map and lot of slimes was there please fix this issue 
thanks , a minecraft player