No one is talking about the slavery problem in Mali
Mali is in the midst of an extended civil war between three parties: the sort-of-legitimate government (backed by France and the U.S.), the nomadic desert-dwelling Tuareg rebels in the North, and the Islamist rebels.
The Tuaregs started the most recent flare-up in the civil war, but the Islamists have stepped in to exploit it. The Tuaregs want their own country split off from Mali (and a few neighboring countries) and WANT THE RIGHT TO OWN SLAVES. Right now the Tuareg have hundreds of thousands of ethnic Africans held as slaves.
This is one of the messy truths of modern Africa: slavery still exists all across the North. It's generally Arab-descended (to vastly simplify) people owning ethnic Africans. It's incredible the world does nothing about this.
But the West has had a reason for playing down the slavery aspect of the Mali civil war. From the very beginning they hoped to exploit the tensions between the Tuaregs and the Islamists and their two divergent agendas. So, no one wanted to play up painting the Tuaregs as slave-holding villains. The media is too stupid and lazy to report anything much more than what they're spoon-fed, especially from such a remote and physically inhospitable location as northern Mali. So, basically, there has been no coverage of slavery even from the most well-meaning news sources.