Odd RT point light behaviour with DX12 (4.26)

Development Rendering
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Hi, I am experiencing very odd behaviour in UE 4.26 with ray tracing when directx12 enabled. Let me show it with some images.
I enabled ray tracing and created extremely bright, red, point light and completely closed it off with walls. Except 1 side, I left very narrow area where light can leak on to some object.
Here the first image is just shows the scene:

RayTracingFail_dx12
RayTracingFail_dx121170×592 272 KB

Now second image is just close up screenshot with:

[/Script/WindowsTargetPlatform.WindowsTargetSettings]
DefaultGraphicsRHI=DefaultGraphicsRHI_DX12

enabled in DefaultEngine.ini file:

dX12_laser_fail_zoom
dX12_laser_fail_zoom1150×605 315 KB

And now last picture without DefaultGraphicsRHI_DX12 option (either when it is just deleted or replaced with DefaultGraphicsRHI_DX11):

lowQuality_no_dx12
lowQuality_no_dx121183×621 322 KB

Second picture has higher visual quality but it is not correct, it need to look like 3rd picture.
3rd picture looks correct but has way lower visual quality.

I am using rtx 2070super with intel cascade lake xeon processor. Windows 10 Build 19044.2364

Can someone englihten me? Does anyone have any idea about this problem?