Hi Andy!

Seriously though, nothing to do with elbow placement or any other Dr Elbow's Cure All nonsense IMVorE.

It's apparent from the images that you do have quite long fingers, a [u]serious[/u] advantage when it comes to fretting guitar. But you're neither forming them correctly for that chord form, and your thumb positioning/placement is just weird for Open G that form. Get those right and the rest should naturally fall into place.

[br]Part of it is that you quite apparently don't have the tactile control or flexibility over your fretting hand and fingers yet. That's entirely normal. Like any new physical activity one is unaccustomed to, that will come with exposure and application over time.

Watch this again, and again if necessary, and note how Lisa is forming that chord.

Now practice.

[br]Make micro adjustments until you get the placement form and tone correct with the sounding of each string correct with out muting any.

If that's still not resonating with you, watch this. Note the thumb and finger placements, the nuance and minutae of which is all well described in detail reinforcing what I've already iterated.

Now practice, practice, practice.

In other words, [u]persevere[/u] until rote.

You [u]will[/u] get it.

[u]But[/u], it takes time with cognizant application. It's not a watch the 3:21s lesson once, apply and you've got it McExercise rote perfect.