NEW YORK—Labor shortages may be the most intractable of the cost risks that companies faced in the latest quarter, and as the earnings season moves into its peak there are signs the problem will persist, some strategists say. Finding and paying for workers is a challenge investors are paying close attention to as third-quarter results come in, with supply bottlenecks and high energy and other commodity prices among other key risks for companies. Warnings have come already from companies in several industries, including healthcare, with hospital operator HCA Healthcare Inc. saying higher labor costs seen in the third quarter could stick around longer because of a shortage of workers. Domino’s Pizza cited a shortage of drivers as it reported recently a rare fall in sales, and FedEx Corp. also cited higher labor costs in September when it cut its full-year forecast. The coming weeks, which bring results from the bulk …