An egg is in the incubator. Why has nothing hatched?
Use the building tier, the egg species and the coop’s available beds to identify which part of incubation is holding the hatch.
Find the correct machine for this egg
Walk inside the Big or Deluxe Coop. The built-in incubator is immediately to the left of the hay hopper. Hold the egg and use it on the incubator; putting an egg in the nesting area or on the floor cannot start incubation. A basic coop lacks this machine. Normal, void, duck and dinosaur eggs use the coop incubator. An ostrich egg instead requires an Ostrich Incubator inside a barn; do not sell the egg because the coop rejects it.
Count for the species you actually loaded
A chicken egg takes about 5 days and 17 hours at standard speed, so do not assume a full five mornings is enough. A dinosaur egg takes roughly twice as long, around 11 days and 7 hours. Coopmaster halves incubation time. Note the day the egg went in and allow for the time of day before treating it as overdue. Go inside the coop after the expected completion; the naming event is the useful success signal.
Reserve a bed before blaming the timer
A Big Coop has room for eight residents and a Deluxe Coop for twelve. A completed egg cannot produce a new resident in a full building. Count all birds and rabbits assigned to that particular coop. Free a bed by moving a resident to a compatible coop with room, then enter the original building again. You do not need to sacrifice a second rare egg to test this: resolve the capacity problem first.