Faulty composition preview
I was working on a project today when the preview window of my composition went completely blank, when I moused over the layers of my composition, the bounding box appeared but the artwork was not viewing. I recall having this problem before and its clearly frustrating to say the least. Several hours of work have been lost.
I reset the preferences with command shift and alt and the composition still won’t view. Other compositions will show. Its just this one that is faulty. I will have to incrementally save from now on to prevent this issue becoming a minor disaster

We really appreciate your post, however, User Voice is primarily for feature requests and bug reports. It appears your issue is more of a troubleshooting problem which could be solved more easily by our support team. You can open a case with them via call or chat at this link: https://helpx.adobe.com/contact.html