DIAGNOSIS The Yogurt function on the Ultra has a specific sequence. If the button just blinks after you press it, it usually means the pot doesn't detect that the contents have reached the correct starting temperature (around 180°F for pasteurization). You have to do that first step manually.
FIX The Ultra's yogurt making is a two-part process. First, you must boil the milk. 1) Pour your milk into the inner pot. 2) Press "Yogurt" once—the display will show "Boil." 3) Press "Adjust" until the screen says "More" (for a full boil). 4) Then press "Start." The pot will heat the milk to near-boiling. When it beeps, it will automatically switch to displaying the target temperature (like 180°F). Let it sit there until the milk cools down to about 110°F (you can speed this up by placing the inner pot in an ice bath). 5) Once cooled, whisk in your yogurt starter. 6) Press "Yogurt" again—now the display should show a time (like 8:00). Use "Adjust" to set your incubation time, then press "Start." Now it will hold the temperature for the set time.
IF THAT DIDN'T WORK Ensure you're using the right inner pot. The yogurt function relies on the precise temperature sensor in the base reading through the bottom of the pot. The original pot is essential. Also, make sure the lid is on and sealed during the incubation phase.
HEADS UP Don't skip the boil/cool step. If you try to add starter to cold milk and just hit "Yogurt," it won't work. The blinking is the pot waiting for you to complete the first part of the programmed sequence.