Here are the steps to do or check if you don't see your lists or segments of prospects or organizations:
Expand the lists/segments panel
The panel with lists and segments can be hidden or revealed by clicking on the arrow button (top left corner).
Prospects or Organizations page?
Overloop allows you to create organizations lists and segments on the Organizations page and prospects lists and segments on the Prospects page. Those are different types of lists.
If you don't see your lists and segments, please, check if you're looking at the correct page: Prospects or Organizations?