The Timeline page currently only shows Assignee icons in the project block at 100% zoom level (as seen in this article https://blog.asana.com/2018/03/new-asana-timeline-view/). If zoomed out to 20%, the assignee icons disappear.
Our projects last longer than 2 days so, in order for this to be useful, being able to see the icons on a lesser zoom is key. The appearance of icons felt very useful to me, until I realized this limitation. If available at other zoom levels, this will help me, as the program manager, to see who’s working on what until when, and bolster my planning and bandwidth management.
I am working on Windows in Chrome Version 66.0.3359.181.