Add "r.LightPropagationVolume = 1" to ConsoleVariables.ini
Open the landscape editor to the "paint" tab
Landscape - Material Paint Tool Crashes - 4.13.1
Painting landscape with LPV crash UE4.13
Fatal Crash when switching to landscape paint tab
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-36933 in the post.