Answer: The red tips are normal in that the new growth should be that color. The loss of foliage is not normal. Based on your description it may be a problem with lack of light so the foliage is adjusting to that, and/or overwatering, and/or a disease problem. This plant actually does better in full sun to partial sun rather than full deep shade. In less light, it will grow thinner and leggier rather than bushy and dense.
During the initial establishment phase it needs soil that is evenly moist like wrung out sponge, not sopping wet/saturated and not dried out. To know if you need to water, dig into the soil with your finger. If it is still damp, do not water yet. When you do water, water slowly and thoroughly so it soaks down deep to the deepest roots. To check your watering, wait a few hours after you water and then dig down to see how far the water reached;sometimes it can be surprising. After a year or two, you would only need to water during dry spells; this shrub is more tolerant of dry soil than, say, azaleas.
It may also be that the side against the hosue has less air circulation, and this could contribute to a disease problem especially if the foliage is left wet after watering. Overwatering could also cause root problems that would then be reflected as foliage symptoms.
I would suggest you consult with your local county extension for a more specific diagnosis and also possibly with your retailer since these are new plants.
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