Steps:
1. Make a new project
2. In Player settings, change windows API settings to DX12
3. Make sure the editor is using DX12
4. Resize the Game View window
Actual Result : The Game View window will scale down the whole UI and it looks broken (see comment)
5. Drag the Game View window back to editor "slots" or resize it to bigger size
Actual Result : Crash

Expected result: No crash and behaves like DX11

Reproducible in :2017.3.0b9, 2017.3.0b4, 2017.3.0b2