Schlumbergera are pretty much pest and disease free with only mealybug being a common pest. However they do have a few physical and cultivation problems.
Shrivelling of the stems can be caused by the plant being in a too hot and sunny situation. However it is often due to root deterioration cause by over or under watering.
Scorch; discolours and damages the stems and is caused by the plant being placed in a situation that is too hot and sunny. These are not desert cacti and would naturally grow in woodland in dappled shade.
Non-flowering could be due to the day length not shortening or/and the temperatures not dropping to mimic autumn. For example, if the plant is near an artificial light source after dark and the temperature doesn’t drop below 18°C.
Flower bud dropping is usually cause by fluctuating temperatures. Too hot by day too cold by night. However, overwatering can also cause flower buds to drop. Plants exposed to cold in florists, at garden centres or in the car are also vulnerable.
Late-flowering; can occur when the temperature has remained to high into autumn.
General poor growth can be a sign of over potting and the pot is too large for the plant; they do like to be snug in a pot. Remove the pot to check on root development. If there is little or no sign of new growth, with minimum disturbance remove excess compost and carefully put it into a smaller pot. This action should encourage new root grow and recovery.