Version Information

lithium-fabric-mc1.21-0.12.5

Expected Behavior

Chicken should spawn from thrown eggs

Actual Behavior

No chicken spawn, or very very very rarely one spawns (see video)

Reproduction Steps

Throw eggs

Other Information

• I tested it with and without lithium, without lithium the chicken spawn normally
• I think it has something to do with an entity limit / mob cap? but it is not quite transparent what the limit is set to and what influences it

https://imgur.com/a/6Mc5x0r

Thank you for the quick analysis and workaround, can confirm mixin.minimal_nonvanilla.collisions.empty_space=false works

Thanks a lot for the report.
Vanilla's check for chicken spawning changed, includes collisions in a special way now. But lithium's new optimization for that was broken.

From my testing the above commit fixes the issue.

Workaround: Add line to config/lithium.properties file:
mixin.minimal_nonvanilla.collisions.empty_space=false