Tri-color lotus (Nymphaea micrantha) not thriving -- ideas?

[Frogmouth Catfish]

I finally got my hands on some Nymphaea micrantha tricolor last spring. I've been searching for it ever since I saw a video on Tank Tested that featured a tank absolutely full of the stuff. When an online store (not the Coop, name redacted!) got them in, I jumped on the chance. They came as very small bulbs, much smaller than the typical dwarf lily or even tiger lotus bulb, which I chalked up to the nature of the species. I split my batch into two different tanks--one with Eco-Complete, and one with a sand substrate. Both have been fed a steady supply of root tabs, liquid ferts, liquid iron, and are growing under medium light--and they're just not getting the growth I was looking for. Their leaves stay very small, on average a dime to quarter-sized, and rarely extend above 4 inches from the substrate, usually hugging close to the bulb. One bulb simply died and became a sad little floating brown lump. The dwarf aquarium lily in the same tank, meanwhile, thrives unabated. Am I missing something with this species? Any ideas?

 

Picture not mine, just representative of what a specimen of this species can look like.

 

[Yanni]

I think it could be related to the winter and summer seasons. I don't know if this is really the case but these lotuses will usually grow a lot during the hotter seasons and die off a little during the colder seasons. This might not be the case but it also might be what inhabitants you have. What are you keeping with it?

[Frogmouth Catfish]

Seasonal is a good point, although I've had it over a year at this point. They're just in community tanks with tetras, corydoras, and other small fish.