Epic changed some of the defaults for creating or importing a regular Landscape in the newer versions of the engine. These new defaults can cause loading problems/freezing when trying to apply an auto paint layer, from any Automaterial. Below is a video going over how to get around that and how to setup the Landscape properly, according to Epic’s docs.

If for whatever reason, the embedded video doesn’t load, please click this link, to go straight to the YouTube video.