Flickering shadows/GI when DrawMaterialToRenderTarget is called per tick in PIE

When DrawMaterialToRenderTarget function is called on tick and actors are spawned in game, the lumen shadow/GI visually flickers. Debugging shows that the lumen screen probes are flickering as well.

Download the licensee's example project ([5.4] Screen Flickering while in PIE (unrealengine.com)) and play in windowed PIE mode.

Repro steps:

1) set "r.ScreenPercentage < 100" ( force the game client view size to be different from the editor client view size)

2) spawn actors periodically

3) call blueprint node DrawMaterialToRenderTarget every tick

4) play in editor and make sure the client view is not in fullscreen