Explained: Why was Shanaka given not out even after getting 'out'?

In a dramatic Asia Cup Super Over, Sri Lanka's Dasun Shanaka survived a clear run-out due to a cricket law technicality. After being given out caught behind, which he reviewed, Shanaka was run out while the ball was deemed "dead" by the umpire's initial decision. DRS overturned the caught-behind, but Law 20 protected him, baffling players.

Explained: Why was Shanaka given not out even after getting 'out'?
In a dramatic Asia Cup Super Over, Sri Lanka's Dasun Shanaka survived a clear run-out due to a cricket law technicality. After being given out caught behind, which he reviewed, Shanaka was run out while the ball was deemed "dead" by the umpire's initial decision. DRS overturned the caught-behind, but Law 20 protected him, baffling players.