Not sure how much to push son here

My 8 year old (AuDHD and anxious) has been taking ukelele for a couple of years. There's a recital once or twice a year but he always declined and I never pressure him to do it. This year however he said he actually wanted to do it much to my surprise. I was really proud of him for branching out and challenging himself. I paid for his spot (like $30 not a huge deal), bought a nice outfit for him and invited family.

Anyway, recital is on Saturday and son has made it clear that he has changed his mind and doesn't want to do it. Straight up refusal. He won't say why he changed his mind but I think he's scared to do it all of a sudden .

Anyway.Not sure what to do here. I was really proud of him for doing something out of his very small comfort zone and I feel like doing this could help his self confidence and grow a bit. He made a commitment and I don't want him to learn that it's okay to back off on commitments. But I don't want to drag him kicking and screaming. Ugh.