Understanding air layering

[miamicuse]

Last few years I have been doing air layering of some of my plants.  Mostly crotons.

I typically strip the outer layer, add some root hormone, spagum moss, and an aluminum foil over it, wait about 2-3 months and most times I end up getting a new root ball ready to pot, and in addition to that I noticed new buds tend to form below the air layer site, as shown below.

This is very interesting to me, because crotons as they get taller and bigger, some of them become very "leggy" and top heavy.  So even if I am not trying to propagate for more crotons, I may do an air layer simply to encourage new growth at a spot so the plant becomes fuller.

So two months ago, I have a Brownea grandiceps with some branches that are bare really long and leggy.   Some branches actually got so long they touched the ground (yes I know they tend to grow this way), so I took one branch, cut it back, and just below the cut location, I stripped it's bark and put spagnum moss with root hormone and wrapped it.  My intention is to stimulate new growth below it.  Well that didn't happen, what happened is new leaves emerged above it.

What happened?  I messed up how?