Although various explanations have been put forward for this unusual behaviour, the most likely cause is an ex ante excess supply of savings relative to investment around the world, with Asia accounting for a large part of the excess global savings.
That said, the outworking of some of the excesses of the earlier period of rapid growth, especially the period just after the financial crisis of 2008, remains a work in progress and a source of risk. But in other ways, one could argue that the global backdrop has improved.