Part of video does not render in RAM preview

Hi there,

I'm a beginner at Adobe After Effects. I am putting together a few videos, I edit them in their own "Project" and then I have a master composition where I simply bring in the aep files into. And I drag them into the layers panel.

It was working fine for a while, and then after I added a few more videos, and tried to preview them (Ram preview) it stops at the old point, never "rendering" the new videos.

No idea how to fix this. I attached a screenshot of how my workspace looks. You can see the green line stops on the left, and then tere is a blank space in the middle and then the green line continues on the right hand side.

Thank you for your help,

Best, Arturas.