How to reproduce:
1. Open the attached 'RenderTextureBlit.zip' project
2. Open 'SampleScene' Scene
3. Select 'ScreenCapture' GameObject in the Hierarchy
4. Deselect 'Render Direct' flag in the Inspector
5. Enter Play Mode
6. Double click on 'Debug RT' RenderTexture and observe that RT outputs screen
7. Exit Play Mode
8. Select 'Render Direct' flag in the Inspector
9. Enter Play Mode
10. Double click on 'Debug RT' RenderTexture

Expected result: Render Texture outputs screen
Actual result: Render Texture is black

Reproducible with: 2018.4.23f1, 2019.4.1f1, 2020.1.0b12, 2020.2.0a14

Notes:
- Using Command Buffer to Blit between current active target to BGRA32 RT results in black picture. However when Blit is done to Render Texture without specified format and then to BGRA32 RT everything works fine
- Bliting without command buffer works with both formats when done directly
- Blitting with command buffer works directly with ARGB32 but not RGBA32
- Blitting directly from active texture into intermediate RT with BGRA32 format works fine