To a world full of fixed-income investors starved of safe assets with attractive yields, China’s government bonds had become a tempting sight in recent years. However, red flags are now being hoisted. A series of government crackdowns on everything from property developers to technology firms is triggering questions about whether a sudden change in regulations could harm foreign investment in the securities. While positive inflation-adjusted interest rates and relatively tame volatility are keeping some fund managers bullish on China’s sovereign debt, the regulatory risk is combining with ...