While I grow these I also have trouble getting them to bloom. However, below are a few notes on Cyrtanthus elatus (synonym: Vallota speciosa) from my bulb society forum which might be of assistance. I'm also emailing you privately and attaching a much longer document on Cyrtanthus in general. Some of the cultivation notes there might apply to your specific plant.

NOTES:

"The form usually cultivated by growers reproduces vegetation at a sometimes alarming rapid rate--the clumps become overcrowded very quickly and, if they are not lifted, split up and replanted on a very regular basis, flowering can cease. They prefer full sun rather than shade and flower mainly in summer."

"Here in the UK people have no problem getting C. elatus to flower. A friend, not a gardener, has one in an out building which flowers every year without fail even though it is rarely watered."

"Cyrtanthus elatus never bloomed for me in all the years that I had it. I have to say that I threw out my last bulbs of C. elatus several years ago! Never again will I waste good greenhouse space on Cyrtanthus elatus."

I have a large pot full of Scarborough Lilies . They originally belonged to my mother in law back in the late 1950's and she gave them to me at that time . They always flower every year in late August here , but in England they flowered in September . They love the sun or very light shade and dont like too much water maybe once a week is best. They like to be outside in summer and in during winter. I only transplant them when they get really crowded as they seem to love being somewhat potbound. When transplanting give them good potting compost
and keep them damp .
A west facing window would not be sunny enough for them