Galarian slowpoke fishing help

The world I am playing on has no properly spawning mushroom fields biome (the only biome that G-slowpoke can spawn in), it only has weird 3x3 areas in the middle of the ocean that show up as mushroom fields when you press f3 and check current biome. They also do not show mushroom fields spawning pokemon on the pokenav. I'm trying to get one via fishing, and am using bait that gives 100% psychic type chance (with a luck of the sea I rod if that changes anything), but in the 10 attempts it is not giving one. are they just rare/need a specific rod enchantment or should i just give up