When crustaceans have trouble shedding their old shell, it's usually caused by poor water quality, a dirty tank, lack of food, or inbreeding (not necessarily in that order).
If the water is good, then a poor diet or inbreeding could be a cause. Cherry shrimp and most other small colourful shrimp are inbred for many generations and this weakens them significantly.
Lack of decent food can cause problems and shrimp do best when fed a varied diet and fed regularly (2-3 times a day). They have a high metabolism and eat a lot for little creatures. If they don't get sufficient food or a good quality food, they can eat heaps but suffer malnutrition, which can lead to health issues.
A dirty substrate can kill shrimp because they spend most of their time around the substrate. Any shrimp aquarium should be gravel cleaned regularly (once a week is good).
Poor water can probably be rules out if you tested it and it was fine, and if you do regular water changes.
You might want to test the tap water for copper and other heavy metals, because low doses of copper can kill invertebrates like shrimp and snails.
If you buy plants for the aquarium, make sure they haven't been treated with anything that kills sails because those chemicals can hang onto plant leaves and kill shrimp too.