In the latest sign of stress in a market pressured by Beijing’s effort to clean up a debt-laden financial system, the yield on 10-year bonds fell to 3.55% on Tuesday, less than the one-year paper’s 3.61%. That is a situation unseen since June 2013, when an unprecedented cash crunch jolted Chinese markets. A so-called yield-curve inversion first surfaced in China a month ago, when the yield on less actively traded five-year bonds broke above that on the popular 10-year bonds.