Part of the issue/discussion here, and the Sumburgh accident as well, is that practice UA's on a ride or in a sim don't fully replicate a true UA.
If you have intact SA, you are not in what we regularly call a UA, you know where you are and effecting a recovery is much easier. This includes the 'eyes closed' practice UA's.
When, for whatever reason, you suddenly realize that your idea of what the a/c is doing/where it is does not match reality, it takes time to accept it, to acquire data, and regain some semblance of SA. If you have marginal VMC, it can be hard, but IMC is very tough!
I've had this happen 3 times in my career. The training UA's we do are great for practicing the latter stages of recovery but do not give insight into prevention, recognition, or acceptance.