They also have cultivars that do not bloom starting at the same time. Most of the ones in my neighborhood are average but I always see a straggler. So some could be late or very late bloomers. They bloom on new wood so avoid pruning once they have leafed out. But generally, young trees (5 years?), insufficient sunlight/water, an over abundance of water/fertilizing cause this issue. Rarer causes: insect infestation and fungal leaf issues like leaf spots or sooty mold and soil nutrient deficiencies.
