I am using the Iron farm idea by avomance from this video

But i want to add a villager breeding dynamic.
So basically i have a small area with 3 villagers where they farm carrots and have access to composters, all inside a glass with a small hatch for babies to get out of.

Outside the glass chamber i put 4 beds.

On the side i've put a zombie with a trap door to be able to turn off the iron golem farm and enable the villager breeder.

I've also got a river system to take the babies away so they're more than 32 (i think) away and it seems to work. i've created 4 babies this way so i think it works.

Before I tested the villager breeder aspect, i was able to have iron golems spawn quite frequently.

I did notice the following requirement. 
Before getting the villagers inside the glass chamber, they have to sleep on the beds at least once. I think this is to register the "village".

And golems were being spawned on top of the glass chamber as per avomance's kill chamber and it was going well.
But when i switch from iron farm to villager breeder, breed some villagers, and back to iron farm, it stops spawning iron golems.

i've done this multiple times now and i've even rebuilt the farm twice in a brand new world.

is there some rule or mechanic that stops iron golem spawns once the villagers breed??

I have attached my game save so you can see the build.