Slack is acclaimed for its great enterprise chat software, but the company also is known for its efforts in hiring women and people of color. CEO Stewart Butterfield is invested in the company's diversity initiatives, the company says and does the right things, and employees consistently tout the startup's achievements and strategies.

And yet, it seems that Slack has begun to hit the same obstacles that often torment the efforts to hire women and minorities for tech companies across Silicon Valley.

Slack on Wednesday released its third annual diversity report, and although the young company was generally able to maintain the representation of its women, Hispanics and African-American, it was able to accomplish only a few substantive gains.

Why was that the case? Since Slack's last diversity report, the company more than doubled its workforce to nearly 800 people. That means that moving the needle is no longer as easy as simply hiring a few more women and minorities. As Slack's headcount grows, making notable gains will continually become a tougher challenge.

"We have always said we want Slack to be a place where people of all different backgrounds thrive," the company said in its report. "This report is part of our commitment to the transparency required to make progress in this space."

For its overall representation of women, Slack saw virtually no change, with the figure staying steady at about 43 percent for its global work force. Hispanic representation among its U.S. employees increased by a percentage point from 5 percent last year to 6 percent now. Slack's best accomplishment was increasing its women in manager positions globally from 43 percent to 48 percent. But, notably, the company doesn't offer a year-over-year comparison for its employment of Black/African-Americans in tech, because of a change in survey methodology. While the company reports a rate of 5 percent for its 2017 U.S. work force, its 2016 figure for its global work force was 7 percent.

"The acquisition of talent is hard right now. The acquisition of women and minorities is particularly hard right now," said Leslie Miley, executive in residence at Venture for America, an organization that trains entrepreneurs. Miley was previously Slack's director of engineering. "If they were able to make gains or remain static while doubling in size -- it's not a victory, but it's not a bad thing."

This is the challenge that plagues major tech companies like Google, Apple and Facebook. While smaller companies and startups can drastically change their demographics with the hiring or departure of a few individuals, bigger companies and fast-growing firms must put in broader efforts to accomplish the same thing.

"Slack has of course hit that wall," Miley said. "But if anything, they haven't gotten ejected from the treadmill yet."

Slack's diversity efforts include a third-party salary audit to ensure women are not paid less than their male counterparts. The company also works with organizations like Code2040, Year Up and Project Include to find more candidates with underrepresented backgrounds and develop strategies for the company's diversity and inclusion efforts.

One key tactic that Miley suggests Slack try is to begin recruiting and hiring folks in more regions. Last year, the company began expanding to offices in places like New York and Toronto, which Miley says is a good start, but if Slack wants to reinvigorate its diversity gains, it should consider expanding to areas where minorities are represented in vast numbers.

"You have to go to where your users are, and users are all over the country and all over the world," Miley said. "Toronto is a great start, but Atlanta and Richmond, Virginia would also be a great start."

Clarification: An earlier version of this article misstated that Slack's employment of Black/African-Americans in tech roles declined in 2017 from 2016. No decline was reported because of a change in the report's methodology from 2016 to 2017. The company says it changed its reporting when it switched its data collection process and it also needed to limit its report to only U.S. employees to comply with the laws of other countries. A comparison using Slack's 2017 methodology results in Black/African-Americans holding 4 percent of tech roles last year compared to 5 percent this year, a company spokeswoman said.