In the egg printer, the timing on the egg incubation is linked to the percentage, meaning that it only updates every percentage update and it doesn't display the correct time left when a time upgrade is used. After the egg finishes incubation, it also goes beyond 0 in the minus for some reason while the egg is already incubated, giving you an incubated egg with -40 percentage. (The egg hatches normally when placed on ground though)
In the egg printer, the timing on the egg incubation is linked to the percentage, meaning that it only updates every percentage update and it doesn't display the correct time left when a time upgrade is used. After the egg finishes incubation, it also goes beyond 0 in the minus for some reason while the egg is already incubated, giving you an incubated egg with -40 percentage. (The egg hatches normally when placed on ground though)