I heard Sai Baba didn't show up to a ceremony he promised to attend. Can you explain what happened with Dev's Udyapan feast?

This is a common misunderstanding. While the devotee, Dev, initially believed Sai Baba had not come to his Udyapan ceremony, Baba later clarified that he had indeed attended. As detailed in Chapter 40, Baba came in the guise of a Sanyasi. He first appeared alone, and Dev was wary. The Sanyasi then promised to return for the meal with two others. He did exactly that, and all three were fed by Dev. However, a 'veil of Maya' prevented Dev from recognizing Baba. It was only after Dev complained to another devotee, Jog, that Baba revealed the truth, stating, 'You did not recognize Me! Why then did you call Me?'