Same issue here. I tried the version 4.18.1 as well, but this time it takes forever to “compile shaders” and uses all my CPU.
Using: MacBook Pro (Retina, 15-inch, Mid 2015)), 2.8 GHz Intel Core i7 (4 cores), 16 GB 1600 MHz DDR3, AMD Radeon R9 M370X 2 GB, Intel Iris Pro 1536 MB.
Given the download size is so big, I am hesitating now to download any other version of Unreal Engine 4.