The first Preview release of 4.12 is now available to download from the launcher. 4.12 and sees the introduction of new features for Sequencer, a non-linear editor with 3d animation editing to allow you to produce in-game cinematics as well as a sequence of shots for film, tv, and previsualization.
To download Preview 1, head to the Epic Games Launcher and select the "Library" tab. Click "Add Versions", and choose 4.12 Preview 1.
You can read up on the fixes included in this release through this forum post from Stephen Ellis. Also be sure to have a look at the known issues list to see what's still outstanding. Please remember these Preview builds are for testing only, and should not be used for the active development of your project.