The last Mageia 6 test release was in June of last year and their next Mageia 6 "stabilization snapshot" has been repeatedly delayed for months.
This next test release of Mageia 6 isn't ready to ship yet, delayed most recently by a nasty partitioning bug. They are hoping to get Mageia 6 Stabilization Snapshot 2 shipped soon. Once that happens, they are going to focus on their remaining blocker bugs to then be able to finally ship Mageia 6 officially.
With Mageia 7 they hope that release won't take as long and will focus on improving critical parts of the stack.
More details via the Mageia.org blog.