Q.Fox Tail Lillies – One Variety Is Flowering But Not The Other
Purchased early this year, the yellow variety are flowering but the pink ‘romance’ are not. There are leaves, which are brown at the tips, and no flower shoots. They are not crowded and are in well drained soil in a sunny position.

Certified GKH Gardening Expert
Unfortunately, it looks like the soil is thick, and remains too wet for too long. These are infections from overly wet soils. Soil with clay content can appear dry within the top inch, but can be saturated further down. This will cause infection.
From here, I would treat with a fungicide, then add earthworms to the area. They will help the soil situation. Other than this, I wouldn't water the area at all, outside of natural rain, unless there is a severe drought. In this case, you will want to make sure that the soil is bone dry down to about 2 or 3 inches between watering.
Here are some articles that will help;
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/ornamental/flowers/foxtail-lily/foxtail-lily-plant.htm