At any given time, 40% to 60% of the company’s staff are people who were previously incarcerated, he says. One is Shaun Higginbotham, who was released from state prison in January 2018 after serving four years and had been unable to find jobs in warehouses and factories. He is now an assistant general manager at Hot Chicken Takeover in Strongsville, Ohio.

“I remember thinking, I’m trying to better myself and do the right thing and nobody’s giving me a break,” said Mr. Higginbotham, who is 40 years old. “I understand why people get out and end up going back.”

‘We do not stack up’

Some workers are changing their tactics, too. Those who are not getting any traction with online job postings are turning to more old-fashioned ways of finding work, such as referrals from friends and family.

Ray Rodriguez was able to get a job with IBM after a professor at Dutchess Community College in Poughkeepsie, N.Y. connected him to one of the managers of IBM’s apprenticeship program. He visited the company’s campus even though he noted that he didn’t have industry experience—something he said other hiring managers mentioned as a strike against him. He was accepted by the apprenticeship program, which offers paid training to qualified candidates without experience, and learned how to be a chip tester.

The job ended a frustrating four-month period of searches for Mr. Rodriguez, who earned an associate degree in electrical technology in 2019. “That’s what I was hoping for,” said Mr. Rodriguez. “For a company to give me a chance.”

Sonam Oberai seized an opening when her husband forwarded her an internal email saying Wayfair Inc., where he worked, was seeking referrals. She had been out of work since 2017, when the senior business systems analyst in human resources technology resigned to take care of a new baby. She started work in July—ending a search that involved roughly 100 applications, she said, all with no response.

“I just couldn’t get my résumé in front of a recruiter no matter how appropriate my résumé was for that position,” she said.

There is no way for workers to know if they were denied a position because of how software systems filter candidates. Still, some are convinced it was a factor. “It’s kind of like you’re racing against everyone applying for the job and an algorithm you don’t understand,” said Verina LeGrand, a U.S. Air Force veteran who had trouble finding a new job after a period when she didn’t work.

Ms. LeGrand was on maternity leave when she was laid off from her pharmaceutical sales job in 2017. She took a break from her job search to care for her children and grieve the death of her husband, a dark period that simply appears on her résumé as two years that she wasn’t employed, she said. In 2019, when she was ready to return, Ms. LeGrand worked with a professional résumé writer. “I got no hits—and I mean absolutely no hits,” said Ms. LeGrand, who is 41. “I can’t even remember the amount of jobs I applied to. I got nothing in return.”

She found work at Fidelity Investments after noticing a banner ad online from reacHire, which develops programs for women re-entering the workforce following a break. She joined the human-resources team and was hired permanently after four months.

“For people like me or other women that have been out of the workforce,” said Ms. LeGrand, who has since been promoted by Fidelity, “we do not stack up against the algorithm.”