To Rick's point that China is working hard to manipulate commodity prices:

China targets 'speculators' to stop commodity boom

https://www.bnnbloomberg.ca/china-vows-zero-tolerance-for-commodities-market-violations-1.1607686

China’s banking regulator has asked lenders to stop selling investment products linked to commodities futures to mom-and-pop buyers, three people with knowledge of the matter told Reuters, to curb investment losses amid volatile commodity prices.
It has also asked lenders to completely unwind their existing books for these products, which they manufacture and sell to individual investors, said the sources, who are involved in and have been briefed on the decision. (my bolding) 
https://www.reuters.com/article/china-banks-commodities/rpt-exclusive-china-bars-banks-from-selling-commodities-linked-products-to-retail-buyers-sources-idUSL2N2ND0LJ