American companies are grappling with a shortage of critical minerals used in daily operations despite China easing some of its export controls, according to industry insiders. After Beijing and Washington agreed to a so-called trade truce last November, the Ministry of Commerce issued a notice suspending a ban on shipments of gallium, germanium and antimony to the US for one year. But China’s dominant position in the global market for these vital raw materials, including heavy rare earths,...