This is one of the widespread D3D Hung crashes that have existed since 4.14. This particular callstack has affected around 300 users. The issue has been successfully reproduced on a home PC.
Dxdiag and log with -d3ddebug are attached
This crash is hardware-dependent and does not reproduce on all systems. Successfully reproduced on a home PC; 4/4 attempts.
The crash seems to require a built-up strain be placed on the GPU. On my home PC, having one Reflection Sphere in the level only crashed after I had swapped out materials on assets, PIE'd, and moved around lights. If I didn't take any other prior actions, then I needed between 2 and 4 Reflection Sphere before the crash would occur.
Fatal error: [Link Removed] [Line: 176] Unreal Engine is exiting due to D3D device being lost. (Error: 0x887A0006 - 'HUNG')
There's no existing public thread on this issue, so head over to AnswerHub just mention UE-40807 in the post.