Both my girls used to self settle fine (with no effort from me, I just laid them down for bed and they slept, I don't know how!) until around that age. It is very common from what I understand. For both of mine it coincided with getting teeth, as in they were different ages when they got teeth and the night waking preceded the teeth whether that be at 6 months or 9 months. I think perhaps they experience a bit of a dull ache that is not enough to make them scream in pain but enough to make it hard for them to get to sleep or go back to sleep after a night time wake up ITMS. But other people say they experience the same with ear infections - where the only sign of the infection was night waking. Then again others say it happens a bit before they learn to crawl (their minds just race at the possibility of movement and they have trouble switching off) or it happens when they are going through a stage of separation anxiety, or it just happens for no reason that they can tell.
Either way it is very common. Try and see in you can determine if there is any pain or discomfort reason behind it, but if there doesn't seem to be it could just be a developmental age and stage thing and cuddles might be the only fix.

As for trying to teach her to self settle, I found during the painful teething time there is no way DD1 would self settle for love or money! But when things were 'normal' I would sit with her, rub her face, pat her tummy and sing to her until she went to sleep and repeat for every sleep. Generally I found first attempt it took 1 hour, next time maybe 20 minutes, next time 5 minutes then pretty much straight to sleep after that.....until the next tooth came along and you just yamn and repeat, yawn and repeat

But as with so many baby things, just remember 'this stage will pass, this stage will pass, this stage will pass'.