My Christmas cactus is healthy in every way,but stopped blooming going on two years now.
Too much nitrogen fertilizer produces lush green growth and few flowers. If you think that might be the case, the solution is easy. Are your cacti allowed to experience the decline in natural sunlight or are they under grow lights? If under lights, put them in a north or east window instead. More details here: https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/how-to-make-a-christmas-cactus-bloom.htm