A friend of mine has a mock orange shrub and he asked me if I knew why his mock orange shrub isn't as fragrant as it was before.
Mock Orange Shrub
Certified GKH Gardening Expert
I would suspect this is due to low temps. Has it been cool where you live? It could also be due to the wonky winter weather most of us experienced. With mild temps across much of the country, many plants and trees budded early. Some of us were then hit by unexpected cold spells, which may have caused considerable damage to the buds--with many failing to open or those that do are either deformed or not as fragrant.