SAN FRANCISCO — Barney Harford was hired late last year to help fix problems at Uber, the ride-hailing company. Instead, he has created new ones.

On a conference call this spring with colleagues, Mr. Harford, the company’s chief operating officer, critiqued a new ad that showed a mixed-race couple, said five people familiar with the conversation. He debated aloud how common the pairing was among the audiences that would see it. He also said he found parts of the ad’s early cut confusing, mixing up two black women in the video because they had similar hairstyles, said the people, who declined to be identified because they have signed nondisclosure agreements.

Though Mr. Harford later told colleagues that he regretted his phrasing, his comments struck many on the call as insensitive about race. They said it was part of a pattern by Mr. Harford in which he talked about women or minorities.

They said Uber employees had since filed several informal and formal complaints to the human resources department, the head of diversity and other top executives about Mr. Harford’s behavior. Dara Khosrowshahi, Uber’s chief executive, was also notified and has addressed the matter directly with Mr. Harford, two Uber employees said.

The conduct is surfacing as Uber has been trying to turn itself around after a tumultuous 2017. The company was rocked last year by accusations of gender discrimination and harassment in its workplace, as well as other issues, ultimately leading to the ouster of the chief executive at the time, Travis Kalanick. After Mr. Khosrowshahi replaced him last fall, Uber pledged to follow a philosophy of being kinder and gentler and to reform itself.

Mr. Harford’s behavior shows how new workplace problems continue to crop up at Uber amid scrutiny of whether its corporate culture is changing. While Mr. Khosrowshahi has made many adjustments to the company in recent months and employees have said Uber has stabilized, internal issues — particularly around diversity — persist.

Mr. Harford, 46, who has been meeting more frequently with Uber’s chief diversity officer, has committed to Mr. Khosrowshahi that he will improve his “blind spots” and undergo coaching, Uber executives said.

“I am humbled and grateful for the feedback I received, which has been eye-opening,” Mr. Harford said in a statement. “Honest feedback given in good faith is something we need more of, and I’m totally committed to acting on it and improving.”

Mr. Khosrowshahi said in a statement: “Cultures are not built or rebuilt overnight. People learn, companies learn, C.E.O.s learn. It’s a process of constant self-reflection and improvement, and it takes work to make real change.”

He added: “I am committed to doing more and doing better as we build a culture where everyone feels they belong, are challenged but respected, and can grow and succeed. We’ll make mistakes along the way, but one thing is certain: We will improve, substantially.”

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Changing a company’s workplace culture is difficult, and other recent incidents at Uber underscore that it is a work in progress. Groups representing black and Hispanic employees sent Mr. Khosrowshahi a letter in recent weeks outlining the difficulties that minorities at Uber have had in the past year with promotions and raises, according to four people familiar with the letter. Mr. Khosrowshahi plans to meet with the groups to discuss the issues before the end of the month.

On Tuesday, Liane Hornsey, chief people officer and one of Uber’s top female executives, resigned after allegations that she disparaged other executives, mistreated subordinates and ignored complaints about workplace discrimination. An investigation by Gibson Dunn, an independent law firm, substantiated some of the claims, according to two people briefed on the findings.

Ms. Hornsey, whose departure was reported earlier by Reuters, did not respond to a request for comment.

Other female executives have also left Uber in recent months. Frances Frei, a Harvard Business School professor who was Uber’s senior vice president of leadership and strategy, departed in February to return to Harvard. Bozoma Saint John, Uber’s chief brand officer, left last month to become chief marketing officer at the Hollywood talent agency Endeavor.

The developments are tricky for Mr. Khosrowshahi, who has made it a mantra at Uber to do the right thing. He is close to Mr. Harford, who was previously the chief executive of the travel site Orbitz.

The two men knew each other from working together at Expedia, the online travel site that Mr. Khosrowshahi previously led as chief executive. They remained in touch after Mr. Harford left Expedia to run Orbitz in 2009, and again after Expedia acquired Orbitz in 2015. Beth Birnbaum, Mr. Harford’s wife, also worked with Mr. Khosrowshahi at Expedia for seven years.

Shortly after Mr. Khosrowshahi brought him to Uber in December, Mr. Harford’s comments began attracting notice, five of the people with knowledge of the situation said.

Mr. Harford became a sponsor of an internal group of female employees called Women of Uber, and he was essentially designated to advocate for the group. But at one meeting this year with the group, he made a series of comments that some felt were insensitive toward women, two employees said.

He also made insensitive comments that upset employees at a meeting with a team that oversees Europe, the Middle East and Africa, the people said. It’s unclear what the comments specifically were.

Several Uber employees said they had grown concerned that a second in command who was habitually insensitive to issues of gender and race might damage Uber’s ability to promote, hire and retain women and minorities. Almost all of the employees who report directly to Mr. Harford are also men; multiple people have told him that he should consider more diverse candidates for leadership positions, according to three people familiar with the conversations.

On Thursday, a call for questions was sent inside Uber to prepare for the company’s weekly staff meeting on Tuesday. Among the top questions — which included concerns about Ms. Hornsey’s departure — one stood out, according to two people who reviewed the list: With not any more women on Uber’s executive leadership team than there were a year ago, how can employees expect diversity and inclusion to change?

The question was “upvoted” by many employees using the company’s internal polling software.