We're going to need a lot more info than that. How have you created your C4D sky?
How are you "importing" it into After Effects?
What version of After Effects? 11.0.4? 12.2.0?
After Effects CC 18.104.22.1684, C4D Lite R14
I simply used menu Create - Environment - Sky. I did same for adding floor and it is well
I'm importing the .C4D file into AE directly.
You are two major updates behind. You should be running AE 12.2.0
Are you in Final Render, Draft Render or Software render mode?
I'm seeing similar behavior in Final and Draft, but not Software.
updated both: AE and C4D the problem stills unsolved.
standard (final). You are right seems to be that problem is only in Standard (final)
I have duplicated it on my end, and I have submitted a bug.
Thanks for bringing this to our attention.
I got clarification on this issue.
This is not a bug - it's actually behaving in a way that makes sense, when looked at in the proper way. For Cinema 4D, a background object like a sky is not truly a part of the render, so the incoming footage considers that part of the footage to be transparent. When you bring it into After Effects, AE removes the transparent parts and shows the layers below or the full transparency. You can stop this from happening by using the Inteprete Footage option to ignore the Alpha.
To do this:
In the Project Window, right click or context click on the C4D file.
From the drop down menu, choose "Interprete Footage", then choose the "Main" sub menu.
Under Alpha, choose to ignore Alpha.
This should bring your sky back.
Thanks for following up, Greg.