As she been in pain recently? Like loudly meowing. Not moving around much?
I've seen this kind of behavior before.
My suggestion is to get an echocardiogram done, and an ultrasound scan on the legs. Could be a blood clot on the area and the reason it's "itchy" is because the legs are somewhat dormant and in some kind of pain. Probably not a bad one as otherwise the cat would be in severe pain and unable to move. But I would get that checked if I were you ASAP. If that's the case she needs medicine to dissolve the cloth ASAP. Check if the paws are cold or blueish, or if the cat has pain if you (gently) pull her legs. You can also cut a nail (very carefully, don't go too deep, don't do this if you're not confident you can't do it properly) and see if she bleeds. If she doesn't bleed or barely bleeds, it's a problem and she needs a vet prescribed medicine combo. And probably some painkillers. Get that checked as soon as you possibly can, it can be a little expensive. But it might just save her life if that's some sort of heart disease.
You might want to ask the opinion of another veterinary as well.
You will also need high quality dry food with low mineral content as to not overload the kidneys and the heart.
Yeah I've wondered if it's pain related prior, but the licking occurs on different legs as well. It's never in the same place. She's quite a happy cat and is quite active/doesn't appear to be in any pain. She had a heart scan prior and was found, to have a low grade heart arrhythmia, which I was told is common and wouldn't cause any problems. Paws are warm. Other than the skin issues, she seems like a healthy cat. I've also wondered if it could be stress related but even the most majestic treatment does not resolve it 👑
I'm back to trying different food again now and I'll see how it goes. I already spend a small fortune on high quality food but I never know if it's actually doing any good, especially if it doesn't clear up her skin.
Failing that I'll have to take her to another vet. They seem a bit dumbfounded by it to be honest and suggest allergy tests that are limited and advise the most effective way to find allergies in cats is through trial and error.