wow in a line. I can only say each to its own needs. This is not uncommon. for an example the Morning Glory as well likes very poor soil. If you give the soil all the "right stuff" you will have 20 foot vines and not one flower. Hens and Chickens is another. Gardening can be difficult this way in that each species has its own requirements. Hence I use pails to give proper soil habitant for some of mine.
Good luck on your vines
reg

My Cardinal Vine is in a pot - under-planted with begonias. The vine grew like crazy - up to the gutters and then it set buds and has been blooming for a month now - it is gorgeous! I have a hook up on the overhang and ran clear fishing line down to a couple of metal tent stakes that I stuck into the pot - the result is that the Cardinal Vine looks like it is climbing thru thin air - you can't see the support! I also did Firecracker Vine, Hyacinth Bean Vine and about anything else I can think of! The Black-Eyed Susan vine was glorious this way and quite the eye catcher! I hope yours is doing great now. I do fertilize my pots and never had a problems with anything not blooming. Other gardeners at the Michigan perennials group have always given me good advice on gardening here in zone 5.

Kiwi in Kalamazoo