Some computers with switchable graphics (such as Optimus) fail to choose a video card and end up on a black screen. This has been reported for MacBook Pro 6,2, MacBook Pro 10,1 Retina, MacBook Pro 15-inch (early 2011) and might affect many others.
For the Mac computers, it is possible to use a third-party application, <http://gfx.io/>, to force integrated graphics only through macOS.Then restart in that special mode that works with Tails.
