Certified GKH Gardening Expert
There are crocus varieties that come up in fall. If you don't have one of these varieties, it could be caused by planting the bulbs too shallowly or by unusual weather. See this article for help:
Planting of your Crocus corms should take place approx 6 to 8 weeks before your first frost and when the ground temperatures are below 60 degrees.
Crocus should be planted 3 to 4 inches deep.
There is little to be done with the plants at this point.
Here is a link with more information.
https://www.gardeningknowhow.com/ornamental/bulbs/crocus/when-to-plant-crocus.htm