I have recently built an Iron golem farm on a multiplayer server (1.15.2). Here is a screenshot from above:
I have tried resetting their profession and changing their beds twice now and waiting for a full day night cycle but that was without success. I understand that multiplayer servers have a global mob cap but even when I am the only one online on the server the Iron Golems don't spawn.
I have 3 villagers in each pod, by the way.
I have a villager breeder nearby, and a place where I keep a ton of villagers pretty close, does that affect the spawning of the iron golems? I do see some Iron Golems spawning near the breeder from time to time.