After effects doesn't preview beyond the green line in the Timeline

The information the other two posts have is correct. 

One note on how to fix your preview issue though.

1. Sometimes AE just stops midway through building the preview (or you stop it prematurely), in this case preview again and let it finish building the rest of your timeline.

2. Sometimes you don't have enough RAM available to preview the entire timeline. In this case change the length of the Work Area Bar (That is the thick gray bar with blue handles just above the green preview line).

You can also go to your Settings/Preferences and in the Memory & Performance section you can lower the RAM reserved for other applications setting to a low as possible to free up more RAM for AE to use.

Hi Elena34091568ptvq,

Welcome to the community.

This is how After Effects preview works. It needs to render and store the cache in RAM (indicated by the green line) before showing the preview. Here are more details: https://community.adobe.com/t5/after-effects-discussions/faq-why-doesn-t-after-effects-preview-in-real-time-like-premiere-pro/td-p/10690804

Hope it helps.

Thanks,

Nishu

https://helpx.adobe.com/after-effects/using/previewing.html

Mylenium