I have had a 50/50 success with the bulb that I got at walmart 4-5 years ago-I still have the lily and they are still growing fine, I frequently cut the roots and plant away from the bulb and plant so the bulb will make a new plant. I also have several that will get buds on them but not grow more than that-they don't rot just don't grow either-the bulbs make a nice looking plant overall and I love the lily pad on top of the water-I have both the green type and the red type.
I got the apon corms and they grew fairly well and I was able to propagate them the same as the lily bulbs-they are a bit more sensitive to changes than the lily and tend to melt with too big of a water change or moving them around..but they will flower for you too in the right location-mine liked my tank that get sun and responded well...neither like to be planted- but I do kinda cram the bottom of the bulb in the substrate a tiny bit to keep them in place once they sprout-otherwise I just drop them in and let them sink to the bottom-if they float I give them a day or so to sink and if not I put them in a shallow dish of water in the window-half rot and half sprout
I have had some that did rot in the tank and I had to toss them-I have maybe 8 lily plants left that are still going strong from 3 bulbs I started with that sprouted and that I propagated-all the apons melted last year and have not sprouted again so I guess they are dead......lol.....or I can't see them through all the other plants in the tank....my tanks are massively planted.....
Here is a pic of a lily pad on top of the water-you can't see this in the pic but it has red dots on the leaf and the leaf under water at the bulb are red