weird behaviour with 3D precomp

I think the problem is the nested comp on layer 2 in your pre-comp. Are there 3D layers in that nested comp?

You also have a light in the pre-comp. That will be ignored when you Collapse transformations. The camera in the main comp and the lights in the main comp will affect the layers in the nested (your pre-comp) comp. 

You should also have a camera in the Main comp rather than relying on the default Active Camera view.

The standard workflow for nesting 3D layers in a pre-comp is only to include the 3D layers.  No lights, no cameras, no 2D layers. 

Cropped screenshots don't tell us anything about your comp. 

I suspect that you may have made the Nested comp (your pre-comp) 3D, you may not be looking at the Active Camera view, or that the flipping pages are driven by a poorly written expression. 

Please embed two more screenshots by dragging them to the reply field instead of uploading them. Make sure you select at least one problem layer in the Pre-comp and press the "u" key twice, and select the Nested comp in the main comp and do the same thing. We should be able to figure it out.