what can we do differently...

so, before you ask your horse to do this...
let's start by getting things clear in your mind

(btw some of the questions above are trick questions, in that there is no definitive answer to them for leg yield, e.g. the neck flexion ones,
but you still should decide and tell your horse which of the options you expect him to perform)

so let's start with a language both horse and rider have a similar level of understanding of....

do the exercise again, but this time physically demonstrate what you want the horse to do
use your arms to represent forelegs,
your legs to represent hindlegs,
and physically 'do' leg yield

ok, be honest, was your first attempt along the lines of stumble sideways on command?

don't worry, that's quite normal,
but again it demonstrates how we really have no genuine comprehension of what we're asking the horse to do
so, as i said previously, the horse doesn't stand a chance...

and staying with the stumble sideways on command theme, isn't that what we often get?
and are you beginning to understand why?

the other variations are
tie your legs and arms in knots,
or come to a shuddering halt within a couple of strides, in a complete tizz of confusion