All incubators, when set to non-continuous, reverts to continuous on loading a game.
I maintain a set number of critters in my ranches and only use the incubators to replenish critters when they die out. Whenever I load any game, the dupes run off to take eggs out of my carefully managed kitchen and load up every incubator. Funny, but a pain to reverse every time.
Build an incubator and set it's the priority to higher than any storage for eggs. Turn off continuous. Save and load again. Watch the dupes run to fill the incubators defaulted to continuous.