When we add new field, we have to run the job of refreshing the data entity. Sometimes it cannot appear in data entity Columns as shown below.
The reason is of not showing the new field in data entity columns list is because of the mapping of the field among staging and data entity. So for resolving this issue we need to regenerate the data mapping of the data entity. By doing this it will map the columns again from scratch and show it to data entity columns list.