It might be a dwarf or small variety :-D Or, if you take it out of the pot and plant it in the ground it might take off like a rocket!!! Mine in the ground always do better than the ones in pots, don't ask me why
How tall is it now? Are both those clumps Daylily? When it finished blooming last year did you keep it in the sun and let the leaves die off naturally? They store energy for the next years growth through the leaves, possibly it didn't get sufficient sun to store much energy. Also, where did you keep it through the cold winter? In the ground they usually will overwinter just fine but in a pot it might have gotten too cold, had to use it's energy to keep alive and doesn't have enough to grow fully and bloom. Just leave it in the sun and water as usual this year, you could get some bulb food and give it a boost for next year. When do Daylillies normally bloom in your area? Daylillies around north Texas just started earlier this month so maybe it isn't warm enough for yours yet.