Maybe related to HDR? I had the same problem, and on a whim I changed HDR settings and the black backdrop to the rain vanished. Upvoted.
Edit:
Tested some, occurs when HDR is on Standard during the fade-to-black after the Cutscene.
Temporarily switching HDR to Low and back seems to fix it.
Low HDR during the fade-to-black works correctly.
Video card/Drivers:
Geforce 660ti, 332.21 drivers