Only cats spawning in iron farm, no iron golems

After updating my existing world (running on a BDS) to 1.17.30, iron golems no longer spawn in my iron farm. I created a test world on my iPad to test iron farm designs, and I can't get iron golems to spawn, only cats. I've left plenty of space for golems to spawn, two levels (both safely within the 6-block vertical space) for them to spawn on, but all I get are cats. Difficulty is normal, mob spawning and daylight cycle are on. Beds are centered in the farm, villagers are linked to the beds and are refreshing their trades. Everything is working as it should except for iron golem spawning.