Despite ongoing conversations about gender equality in the workplace, progress has been slow--if not stalled. Blind spots may help answer the question as to why women hold fewer senior positions than men.

That's according to a new joint report from McKinsey & Co. and Sheryl Sandberg's LeanIn.Org released on Tuesday. More than 60 percent of men believe their company is doing what's necessary to improve gender diversity, the report found.

What's more, 50 percent of men think that their managers are considering a diverse pool of candidates to fill open positions. The report, which Sandberg calls the largest of its kind, reflects input from 222 companies that employ more than 12 million people combined.

Almost half of men think it's sufficient when one in 10 senior leaders in the company is a woman--and a third of women agree. But women make up half the population, Sandberg argues in a Wall Street Journal article, and when people accept a leadership team that's only 10 percent women, they can become too comfortable with the status quo.

Only one of five C-suite executives is a woman and not even one in 30 is a woman of color. But women are also underrepresented throughout the workplace, and it's not because of attrition or for a lack of asking. Women request promotions at the same rate as their male counterparts but are promoted less often.

Sandberg offered some insight as to how companies can do better. She advises businesses to make a case for supporting women and back it up with numbers. She also suggested companies ensure managers understand the importance of equality and resist a one-size-fits-all approach.