When you are using a custom field to do a search on the customer list. it changes the way the customer list appears. After the search is finished and you X-out of the search, the list goes into Flat view instead of Hierarchical view.
To change the list back to Hierarchical view, Right click on a customer name and click the Hierarchical View.
At Intuit, we strive to provide the highest quality product by assigning resources to address the issues with the biggest customer impact. In some cases such as this one, a fix will not be immediately available but may still be included in a future release.
Any future updates on this issue will be included in this help article.