Hello, 

Thank you for contacting Ask Extension. Looking at the pictures that you sent, there are a few issues that I can see. First off, a Northern exposure is not a good place for a viburnum. Between the cold winds and a small amount of sun, that could be one of the reasons that it has not flowered. It should be more in a southern area to get the sun to flower. Again, looking at the pictures, the mulch is too close to the trunk. You would want to remove it back about 5-6 inches from the trunk. 

I believe that the damage shown in the pictures is leaf curl.  Leaf curl is a common problem, particularly early in the spring/summer season. There are several potential causes for viburnum leaf curl. I think that the best bet is aphids or downy mildew.

Snowball aphids (Neoceruraphis viburnicola) most often occur on European cranberry bush and snowball viburnums. They can cause twisting and curling of the young growth. These aphids are gray to dark green and feed in clusters at the tips of the branches, causing leaf curl. Look for honeydew and sooty mold. Large shrubs and trees usually outgrow aphid damage during the growing season because beneficial insects reduce aphid populations below damaging numbers. The aphids may be gone by now and there is really no need to treat them unless leaf damage is extensive. There is more on aphids at https://extension.umd.edu/resource/aphids-trees-and-shrubs and also help you to identify them.

Another possibility is Downy mildew (Plasmorpha viburni ). This presents as leaf curl with leaf spots are first yellow then brown. The spots may be angular or have feathery edges depending on species of viburnum. Fuzzy, grayish-white areas of fungal growth may be visible on underside of blotches. The spots may coalesce into large blotches. The leaves become distorted and in severe cases, infected leaves may fall. There is more information on Downy mildew at https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/viburnum/twistedcurledleaves.html

Be advised that horticultural oil should not be applied when temperatures are above 85F degrees, and over application of insecticidal soaps can sometimes burn leaves.

Viburnum leaf beetle can cause leaf curl but there should be holes eaten in the leaves and some leaves should be skeletonized. Cold damage may also cause leaf curl early in the season but it is a bit late for this to be an issue.

Looking at the plant, you might have to do some rejuvenation to it.  Pruning back any branches that have no leaves on them or branches that are crossing. Do not take more that 1/3 of the entire plant. This will encourage the viburnum to fill in and have more leaves to provide photosynthesis to the plant to provide the needed food to encourage blooming. It will not bloom this year, but should next year.

I have included a publication for further reference. If we can be of further help, let us know.

https://hgic.clemson.edu/factsheet/viburnum-diseases-insect-pests/