Hello Peta
Nice to hear from you again!
This is an interesting question you pose… this is obviously perplexing you to some degree.
I am wondering about how you are approaching this pose (and indeed if this is an issue of difference in tightness/flexibility of one hip to the other). I wonder if you can do an experiment for me for the next couple of classes. Instead of trying to lock out your legs, try lifting your hips. It sounds similar but the focus is different. Pull hard on your heels. I assume your body is hard against your legs, right? Think of RELAXING the muscles that you don’t need for this pose – those around the hips and the back. Think release, and then lift the hips. See if the different focus on your pose – from straightening legs to surrendering your hips – makes a difference.
It may, it may not! But get back to me and we can work it out.
Namaste
Gabrielle 🙂