C.mastersii x C.sinense advise

[wonderlen3000]

You need at least east or south exposure. sinesii is a warm growing one and mastersii is the cooler growing so, it should do well in intermediate temperature. And Cym. like at least 5-10'C temp flautuation between day and night. I used to grown mine in apartment too and most really struggle because the temp is always the same. If you can adjust it, ex. make it cooler at night it might bloom.

Or you can put it on balcony, from May till frost, it should flower.