Issue
The description of a catalog item does not show up when the item is opened/viewed on mobile web ($m.do or $mobile.do) or on the classic mobile app.
Release
Any releases that use classic Mobile
Cause
The description field on sc_cat_item table is of type HTML.
Resolution
Convert the field type of description on sc_cat_item from HTML to Translated HTML (OOB it's Translated HTML).
Related Links
More information regarding changing a field's data type: Dictionary entry data types