Well that is super weird. I think the tall grass masked most of them during testing. A permanent fix for this is to just lower the spawn weights in the config until I get a more permanent fix out.

I noticed that even when set to 0, they still spawn.

Lowered spawn rate in 1.4.0, reset your config.

This is in 1.4.0. Generated a Flat World to do some experimenting. Doesn't seem to generate these quantities in a regular world.