Why do some Muscovy duck eggs in the clutch not all hatch?

Not all Muscovy duck eggs in a clutch may hatch due to various factors such as fertilization issues, genetic problems, or environmental conditions. Eggs may also be more vulnerable to temperature fluctuations or humidity levels during incubation, which can affect embryo development. Additionally, some eggs may be laid later and not receive enough time to develop fully before the incubation period ends. Lastly, predation or poor nesting conditions can lead to eggs being damaged or abandoned.