This issue should be resolved with patch 0.4.3. If you continue to experience this issue, please reach out to us through our support site to let us know.
Some creatures are spawning inside rocks or under terrain. This can also affect the spawning of ant eggs.
If creatures get out of bounds, you can go to the Game Preview Debug tab in the Pause Menu to select the Fix Creature Locations button.
ME-6531, ME-6813, ME-7239